For Democrats:
IA: Chet Culver or Tom Vislack would give Grassley a much stronger fight.
I'm not so sure about Culver. For reasons I'm not entirely sure of, many Iowa Dems still have a really bitter taste from him in their mouths. I have one Democratic friend who absolutely abhors the guy, and I'm not entirely sure why.
Plus, keep in mind, that race really wasn't on Democrats' radar until about a month before the filing deadline.
For Democrats, I think the biggest recruitment failure was getting anybody notable to run for senate in Georgia. It's pretty clear national Dems want to target Georgia, and most agree that of all the states in the South, it will probably be one of the first states that swings back to the Democrats. All they got was a wealthy businessman who filed at the very last minute. North Carolina is a pretty close second, but I'm betting a lot of potential candidates were scared off by how much money was spent on that race by both parties in 2014, so I'm not entirely shocked nobody notable came out of North Carolina.
For Republicans, easily Colorado. They proved last cycle that they can make a race competitive that wasn't supposed to be (before Gardner jumped in, Udall looked like a shoo-in for reelection). This year, Bennet started off as extremely vulnerable, but now he looks like a good bet for reelection. The best the GOP could do was a ton of people who have zero name recognition. I still remember last cycle once Gardner jumped in pretty much every other challenger deferred to him, but this year the field kept growing and growing and nobody withdrew.
Sorry, I don't live in Iowa, so I assumed as a former governor he'd be stronger than the Democratic candidate this year, plus I've seen here and there speculation of him making a comeback. I didn't know much about him, so I didn think he'd be that unpopular. And yes, in Colorado, all of the candidates are weak. Keyser is the least weak, but he's still not that strong.
