Nightmare Senate Scenario for Dems

[Mister Mets]

It's possible, but unlikely.

The advantage for Democrats is that it's unlikely that the same party will have an awesome 2016 and 2018.

The party that does well in 2016 Senate races will likely win the White House, which means they'll probably not have a great midterm. That said, Republicans did so badly in 2012 that it won't take much to pick up seats in 2018. Democrats will be defending 25 Senate seats. Republicans can win only a third of the races, and they'll pick up three seats.

[Mister Mets]

Basically, it will probably stay ugly for Dems outside of presidential elections until the midterm electorate gets about 10% more diverse.  I'm not even sure that a 2006 style midterm with a GOP president with underwater approvals is possible in our world. 

It should be. Demographics haven't got less favorable for Democrats, except in the sense of Obama voters changing their minds.

2018 with Hillary will be ugly, but I don't see any way there wouldn't be a net gain for the Democrats in 2016.

Not that difficult -- NV is a 50/50 proposition at best, and CO is definitely vulnerable. None of the Republican seats look like they will be gimmes, like MT/WV were this year. Democrats are definitely heavily favored to take seats in 2016, but it's the way Republicans were heavily favored to gain seats in 2012 -- the chance of it not occurring exists.

And under a Republican Presidency, 2018 could be a net loss of seats too. Only MO looks like a really certain GOP pickup, and in a good Democratic year it's plausible y'all could gain AZ and NV and hold your vulnerable Northern seats.

Bennet ain't losing if Hillary is winning the state.

He could be a candidate for Veep.

A major problem making predictions four years out is that there are a lot of unknowns. People will have scandals. Some will leave the Senate for good reasons. It's likely that there will be some primary losses. Right now, we seem to have the default expectation that every incumbent will run for reelection.

Frighteningly plausible. Hell, Toomey and Johnson could pull it out.

I'd like to see what a Johnson/Hillary Clinton voter looks like.

I'd imagine they'd be interested in resumes. HRC as Secretary of State/ first lady. Johnson as manufacturer.

[Mister Mets]

I fail to see how in any scenario that has the Democrats retaining the White House in 2016, that they don't also take back Florida, Illinois, Pennsylvania, and Wisconsin once their voters who don't bother coming out for midterms show up.  Alaska, Arizona (only if McCain doesn't run), North Carolina, and Ohio would also be possible Democratic gains in that case.

A Republican filibuster-proof majority in the Senate in 2018 requires at a minimum that the Republicans win the White House in 2016.  Even then, it is unlikely.

The links between presidential elections and Senate races aren't always as clear.

It's possible that Democrats keep the White House while losing Florida. So that might help Rubio.

It's also entirely normal for candidates for Senate to run behind or ahead of the party's nominee for President. Incumbency is generally worth a few points. In 2012, Democratic incumbents won senate elections in several states Romney carried: Missouri, Montana, and West Virginia. Meanwhile, a Republican incumbent won in Nevada. Scott Brown lost by seven points in a state Romney lost by 23, so he still ran well ahead of the presidential ticket.

Also, unless the Republican president thwarts his party's extremist agenda he is never going to have 50/50 approvals. The Democrats will almost unanimously hate him, just as much Republicans hate Obama, and they will be motivated this time to go to the midterm polls.
Polarization works in two ways you know.

Look at how the guy took on the mission of pushing Bush's partial privatization of Social Security (as a Sentor representing Pennsylvania).

And look what happened to him two years later.

Republicans are better suited to opposing Presidents. A party that is philosophically in favor of reducing spending is tougher to negotiate with.