GOP best scenario for US Senate, 2018

[SingingAnalyst]

I realize this scenario is unlikely, but not outlandishly so: the Dow passed 26k and unemployment held steady at 4.1%, and may drop further.

GOP keeps all seats they currently hold:

In AZ, McSally wins GOP primary over a divided field and narrowly defeats Krysten Sinema; Green Party candidate Eva Aguirre siphons off some left-wing votes.

In NV, Heller holds on.

In TN, Blackburn holds on against Bredesen.

In TX, Cruz holds on.

In UT, Mia Love wins the GOP primary and narrowly defeats Jenny Wilson, becoming the second Black GOP Senator since 1978 and the first Black female GOP Senator since Reconstruction (or ever?)

The GOP picks up 4 US Senate seats held by Dems:

In IN, Rokita defeats Donnelly.

In MO, Hawley defeats McCaskill.

In MT, Rosendale defeats Tester with Tom Breck (G) in mid- to high-single digits.

In ND, Campbell defeats Heitkamp.

Result: R 55, D 45.

Can anyone improve on this (from a GOP perpsective that is not outlandishly unlikely?)

[KingSweden]

That’d result in 55 R, btw

[UncleSam]

I think that Heller holding on is borderline outlandish and is at the very least extremely unlikely.

I don't think it's outlandish for Rs to pick up all five Romney states and one of Ohio/Florida, however. IMO this is actually more likely to happen than that Heller wins.

Best case scenarios are tricky because this far out it's more about predicting the environment and less about data or individual races. I'd suggest people chill wih the predictions or scenarios until after th primaries, but let's be real I think people's heads would sooner explode than refrain from conducting and virulently defending highly speculative prognostications way in advance of any real information.

[SingingAnalyst]

That’d result in 55 R, btw

Thanks, I modified the OP.

[GeorgiaModerate]

I think that Heller holding on is borderline outlandish and is at the very least extremely unlikely.

I don't think it's outlandish for Rs to pick up all five Romney states and one of Ohio/Florida, however. IMO this is actually more likely to happen than that Heller wins.

Best case scenarios are tricky because this far out it's more about predicting the environment and less about data or individual races. I'd suggest people chill wih the predictions or scenarios until after th primaries, but let's be real I think people's heads would sooner explode than refrain from conducting and virulently defending highly speculative prognostications way in advance of any real information.

Best summary of Atlas ever.

[SingingAnalyst]

I think that Heller holding on is borderline outlandish and is at the very least extremely unlikely.

I don't think it's outlandish for Rs to pick up all five Romney states and one of Ohio/Florida, however. IMO this is actually more likely to happen than that Heller wins.

Best case scenarios are tricky because this far out it's more about predicting the environment and less about data or individual races. I'd suggest people chill wih the predictions or scenarios until after th primaries, but let's be real I think people's heads would sooner explode than refrain from conducting and virulently defending highly speculative prognostications way in advance of any real information.

Best summary of Atlas ever.

Thanks! I'll try not to be too "virulent" in my defense of this or any other highly speculative prognostication. :-)

I didn't realize Heller was so vulnerable.

To be fair, one post proposed how the Dems could obtain a 72-28 supermajority after the 2022 elections, while admitting it was super-unlikely.

[100% pro-life no matter what]

The best case scenario is that following the tax bill (and changes in tone), Trump's approval somehow skyrockets to about 55% and every state votes the same way it did for president except for MN-special and the Republicans have a net gain of ten seats (picking up 11 and losing Heller's seat).  61-39 GOP.  It's unlikely, but less unlikely than the people saying that Democrats could pick up TN, TX, and MS.  In the House, this scenario would likely correspond to minimal gains in either direction.

[GeorgiaModerate]

The best case scenario is that following the tax bill (and changes in tone), Trump's approval somehow skyrockets to about 55% and every state votes the same way it did for president except for MN-special and the Republicans have a net gain of ten seats (picking up 11 and losing Heller's seat).  61-39 GOP.  It's unlikely, but less unlikely than the people saying that Democrats could pick up TN, TX, and MS.  In the House, this scenario would likely correspond to minimal gains in either direction.

Both scenarios are very unlikely, but I think you've got their relative likelihood reversed.  If Trump's approval drops to around 30, it's plausible that the D's could pick up TN, TX, and MS (assuming a special to replace Cochran).  He's a lot closer to 30 than 55.

[Greedo punched first]

Best case scenario for GOP
GOP defeats Smith, Klobuchar still wins

Worst case scenario for GOP
1 Democratic pickup in special (Cochran and Isakson resign, Democrats win special in both MS and GA, Wicker still wins)
Klobuchar and Smith win
2 Democratic pickups (Sinema wins, McCain resigns, Democrat wins AZ special)

[GeorgiaModerate]

Best case scenario for GOP
GOP defeats Smith, Klobuchar still wins

Worst case scenario for GOP
1 Democratic pickup in special (Cochran and Isakson resign, Democrats win special in both MS and GA, Wicker still wins)
Klobuchar and Smith win
2 Democratic pickups (Sinema wins, McCain resigns, Democrat wins AZ special)

Your numbers are off in the worst case scenario.  You have D's winning 3 specials (MS, GA, and AZ) and two others (AZ and NV -- you don't mention NV, but it's colored red and a likely pickup).  That's 5 total pickups, not 3.

[GeorgiaModerate]

Here are my ratings and how they fit into various scenarios.  Definitions:

Safe: The outcome is all but certain.  It would take a huge unexpected event to change this.

Likely: I would be surprised if the favorite lost, but it's conceivable in a big enough wave.

Lean: One side has a definite advantage, but neither outcome would be a real surprise.

Tilt: It's very close, but if forced to choose there's one I'd pick.

Tossup: I don't have a clue.

My ratings, including potential special elections if Cochran or McCain resigns:

Safe D/I (14): CA, CT, DE, HI, MA, MD, ME, MN (Klobuchar), NM, NY, RI, VA, VT, WA
Likely D (5): FL, MI, MN (special), NJ, WI
Lean D (7): AZ (Flake), NV, OH, MT, ND, PA, WV
Tilt D (1 or 2): AZ (possible special), IN
Tossup (1): MO
Lean R (1): TN (assuming Bredesen vs Blackburn)
Likely R (1 or 2): MS (possible special), TX
Safe R (4) : MS (Wicker), NE, UT, WY

Based on these ratings, there are various scenarios:

The most likely scenario is: no AZ or MS special, and all the Lean/Likely races go that way.  This leaves MO and IN as very close races.  Both of these are close to a coin flip, so statistically it's likely that they split.  So the most likely outcome is D+1 (gain AZ, NV; lose MO), with a range of +/- 1 seat because MO & IN could go either way.

The best realistically plausible Democratic gain: they win everything Lean R or more favorable.  This is D+4 if McCain resigns, D+3 if he doesn't.  

The best conceivable Democratic gain: they win everything Likely R or more favorable, including specials in AZ and MS.  This is D+6.

The best realistically plausible Republican gain: they win everything Lean D or more favorable.  This is R+8.

The best conceivable Republican gain: they win everything Likely D or more favorable.  This is R+13.

[King Lear]

This is the absolute best case scenario for Senate Republicans.

2018 Senate Elections

2018 Senate Results:
Republicans: 61 (+10)
Democrats: 39 (-10)
And here’s the results in the competitive Senate Races.
Missouri:
Josh Hawley: 58% WINNER
Clarie McCaskill: 41%
Indiana:
Luke Messer: 56% WINNER
Joe Donnelly: 42%
North Dakota:
Tom Campbell: 57% WINNER
Heidi Hentkemp: 42%
Montana:
Matt Rosendale: 55% WINNER
Jon Tester: 43%
West Virginia:
Even Jenkins: 54% WINNER
Joe Manchin: 44%
Ohio:
Jim Renacci: 53% WINNER
Sherrod Brown: 45%
Florida:
Rick Scott: 52% WINNER
Bill Nelson: 47%
Pennsylvania:
Lou Barletta: 51% WINNER
Bob Casey: 48%
Wisconsin:
Kevin Nickolson: 50% WINNER
Tammy Baldwin: 48%
Michigan:
Bob Carr: 49% WINNER
Debie Stabenow: 48%
Arizona:
Martha McSally: 54% WINNER
Krysten Sinema: 44%
Nevada:
Dean Heller: 51% WINNER
Jack Rosen: 46%

[Orser67]

Safe D/I (14): CA, CT, DE, HI, MA, MD, ME, MN (Klobuchar), NM, NY, RI, VA, VT, WA
Likely D (5): FL, MI, MN (special), NJ, WI
Lean D (7): AZ (Flake), NV, OH, MT, ND, PA, WV
Tilt D (1 or 2): AZ (possible special), IN
Tossup (1): MO
Lean R (1): TN (assuming Bredesen vs Blackburn)
Likely R (1 or 2): MS (possible special), TX
Safe R (4) : MS (Wicker), NE, UT, WY

The best remotely plausible Republican gain: they win everything Lean D or more favorable.  This is R+8.

I agree with everything but FL. You don't think it's remotely plausible that Republicans win there?

[GeorgiaModerate]

Safe D/I (14): CA, CT, DE, HI, MA, MD, ME, MN (Klobuchar), NM, NY, RI, VA, VT, WA
Likely D (5): FL, MI, MN (special), NJ, WI
Lean D (7): AZ (Flake), NV, OH, MT, ND, PA, WV
Tilt D (1 or 2): AZ (possible special), IN
Tossup (1): MO
Lean R (1): TN (assuming Bredesen vs Blackburn)
Likely R (1 or 2): MS (possible special), TX
Safe R (4) : MS (Wicker), NE, UT, WY

The best remotely plausible Republican gain: they win everything Lean D or more favorable.  This is R+8.

I agree with everything but FL. You don't think it's remotely plausible that Republicans win there?

The biggest struggle I had was whether to rate FL as Likely D or Lean D (which would have moved it into the remotely plausible group).  In the end, I decided that the massive influx of displaced Puerto Ricans pushes it to Likely; at this point, it really would surprise me if Nelson lost.  Without that, it would have been Lean.

"Remotely plausible" is probably a bad way to phrase it.  "Realistically plausible" is perhaps closer to what I intended.  I'm going to modify my OP accordingly.  Thanks for pointing this out.

[Greedo punched first]

Best case scenario for GOP
GOP defeats Smith, Klobuchar still wins

Worst case scenario for GOP
1 Democratic pickup in special (Cochran and Isakson resign, Democrats win special in both MS and GA, Wicker still wins)
Klobuchar and Smith win
2 Democratic pickups (Sinema wins, McCain resigns, Democrat wins AZ special)

Your numbers are off in the worst case scenario.  You have D's winning 3 specials (MS, GA, and AZ) and two others (AZ and NV -- you don't mention NV, but it's colored red and a likely pickup).  That's 5 total pickups, not 3.

Green, yellow, and brown mean states with special elections. NV is red because there won't be a special election. The 3 pickups I mentioned aren't in red because they only refer to the states with special elections. I actually meant 7 Democratic pickups total (GA special, AZ, AZ special, MS special, TN, TX, and NV). AZ with 2 elections (1 special), MS with 2 elections (D wins special, but other D loses to Wicker), and GA with only 1 special.

[Virginiá]

@King Lear - Making some of the other reach targets close winning margins doesn't make them any more believable.

Even for a Republican hack masquerading as a concerned Democrat, you should at least stick to what is believable / plausible. No party that controls the White House has made double digit (nor mid-high single digits) Senate gains since 1934, and that election had very specific and obvious circumstances that enabled such gains. There are good reasons why this rarely ever happens, if you cared to think about it. Even if Trump's approval ratings spiked to 65% by November, 10 seats is still highly unlikely.

[Greedo punched first]

Safe D/I (14): CA, CT, DE, HI, MA, MD, ME, MN (Klobuchar), NM, NY, RI, VA, VT, WA
Likely D (5): FL, MI, MN (special), NJ, WI
Lean D (7): AZ (Flake), NV, OH, MT, ND, PA, WV
Tilt D (1 or 2): AZ (possible special), IN
Tossup (1): MO
Lean R (1): TN (assuming Bredesen vs Blackburn)
Likely R (1 or 2): MS (possible special), TX
Safe R (4) : MS (Wicker), NE, UT, WY

The best remotely plausible Republican gain: they win everything Lean D or more favorable.  This is R+8.

I agree with everything but FL. You don't think it's remotely plausible that Republicans win there?

The biggest struggle I had was whether to rate FL as Likely D or Lean D (which would have moved it into the remotely plausible group).  In the end, I decided that the massive influx of displaced Puerto Ricans pushes it to Likely; at this point, it really would surprise me if Nelson lost.  Without that, it would have been Lean.

"Remotely plausible" is probably a bad way to phrase it.  "Realistically plausible" is perhaps closer to what I intended.  I'm going to modify my OP accordingly.  Thanks for pointing this out.

Rick Scott has a 55% approval rating and is leading Bill Nelson in recent polling.

Nelson leads in the latest poll and every poll with a sample size of at least 700.

[Coolface Sock #42069]

Best case scenario for GOP
GOP defeats Smith, Klobuchar still wins

Worst case scenario for GOP
1 Democratic pickup in special (Cochran and Isakson resign, Democrats win special in both MS and GA, Wicker still wins)
Klobuchar and Smith win
2 Democratic pickups (Sinema wins, McCain resigns, Democrat wins AZ special)

Illinois does not have a Senate election this year.

[Orser67]

A good election: R+2

Take 3/5 of the red states (ND, MT, WV, IN, MO) while defending one of AZ or NV

Semi-plausible best case: R+7

Hold all seats, sweep the red states (ND, MT, WV, IN, MO), pick up a couple swing states (FL, OH, PA, WI, maybe MN-special)

Best best case: R+11

Hold all seats, sweep the red states (ND, MT, WV, IN, MO), sweep the swing states (FL, OH, PA, WI, MN-special), pick up a seat in a light blue state (MI, MN-regular, VA, NM, NJ).

[Greedo punched first]

Correction: No Senate race in IL.
Best case scenario for GOP
GOP defeats Smith, Klobuchar still wins

Worst case scenario for GOP
1 Democratic pickup in special (Cochran and Isakson resign, Democrats win special in both MS and GA, Wicker still wins)
Klobuchar and Smith win
2 Democratic pickups (Sinema wins, McCain resigns, Democrat wins AZ special)

[Greedo punched first]

Republicans win MO, IN, WV, OH, MT and one other state
Democrats win NV

Republicans win ND, MO, IN, WV, FL, MI, PA, OH, ME, MN-Special, maybe VA and NJ as well!
Democrats win AZ

No way the GOP wins NJ, ME, or VA. Ralph Northam won VA by a wider margin than Hillary Clinton. Northam even did it in an off year. Angus King is very popular. King would almost certainly win against a Republican. King would easily defeat LePage. The NRCC even suggested Poliquin might be vulnerable in ME-02. Chris Christie killed the NJGOP. Menendez would just go down in a primary if he doesn't win.

[Coolface Sock #42069]

This is the absolute best case scenario for Senate Republicans.

2018 Senate Elections

2018 Senate Results:
Republicans: 61 (+10)
Democrats: 39 (-10)
And here’s the results in the competitive Senate Races.
Missouri:
Josh Hawley: 58% WINNER
Clarie McCaskill: 41%
Indiana:
Luke Messer: 56% WINNER
Joe Donnelly: 42%
North Dakota:
Tom Campbell: 57% WINNER
Heidi Hentkemp: 42%
Montana:
Matt Rosendale: 55% WINNER
Jon Tester: 43%
West Virginia:
Even Jenkins: 54% WINNER
Joe Manchin: 44%
Ohio:
Jim Renacci: 53% WINNER
Sherrod Brown: 45%
Florida:
Rick Scott: 52% WINNER
Bill Nelson: 47%
Pennsylvania:
Lou Barletta: 51% WINNER
Bob Casey: 48%
Wisconsin:
Kevin Nickolson: 50% WINNER
Tammy Baldwin: 48%
Michigan:
Bob Carr: 49% WINNER
Debie Stabenow: 48%
Arizona:
Martha McSally: 54% WINNER
Krysten Sinema: 44%
Nevada:
Dean Heller: 51% WINNER
Jack Rosen: 46%

Whoa dude, you don't think the GOP could win in Maine or Minnesota after Trump almost carried both states?

[GeorgiaModerate]

It's Kyrsten Sinema, not Krysten (as in the post quoted previously.)