Pick-ups:
Indiana (Lean R): A lot will depend on who Donnelly's opponent is, and while I have no doubt that he'll massively overperform Clinton's 2016 performance, he is running in a tough state that often isn't kind to incumbents. He'll need some wind at his back to win.
Missouri (Tilt/Lean R): McCaskill is definitely in trouble, but she's been labeled DOA before, and we saw how that worked out for Republicans. Had she beaten Akin by only 2-3%, it would be hard to see her winning, but since she won by 16%, clearly she has more appeal in Missouri than some would like to give her credit for. She's not a bad campaigner, and while she's in for the fight of her political life, counting her out this early is foolish.
Nevada (Toss-Up/Tilt D): Heller got very fortunate in 2012, and still just squeaked by. Nevada's also not trending in a favorable way for him. Again, though, much will depend on his opponent, and Rosen might be too inexperienced/untested on a statewide level. Since it will be a Trump midterm, though, Heller will likely face some headwinds.
North Dakota (Toss-Up/Tilt R): People seem to be ridiculously opinionated on this race. I think the assertion that Heitkamp has special appeal in North Dakota is accurate, but that doesn't make her a shoo-in, that just gives her a fighting chance. This is a state that has moved significantly to the right since 2012, and while we don't know who her opponent will be yet, there's a good chance he/she will be more competent than Berg, who she just barely beat.
Competitive holds:
Arizona (Lean R): Flake isn't very popular, and a strong Democratic challenger will definitely endanger him, but Arizona remains a tough state for Democrats. Republicans may not love Flake, but that doesn't mean they'll turn their backs on him and allow a Democrat to win.
Florida (Lean D): Nelson is decently popular, but he's running in a state that is chronically competitive, and his likely opponent, Rick Scott, will be able to self-fund his campaign. Scott, however, isn't exactly beloved, and just squeaked by twice in Republican wave years, so he won't have an easy time unseating a Democratic incumbent.
Michigan (Likely D): Stabenow will probably be fine, especially since the Republican bench here isn't very strong.
Montana (Toss-Up/Tilt D): Both of Tester's wins were impressive, but they were also narrow, so he definitely can't rest easy, even in a Trump midterm. The fact that his opponent won't be Zinke or Fox definitely helps him, though.
Ohio (Lean D): Mandel may look in good position right now, but so do Strickland in 2015, and we saw how that ended. Rematches have rarely worked out well for the loser, and while the results in Ohio in 2016 should make Brown at least a little nervous, he has much more appeal than Clinton did here.
Pennsylvania (Likely D): As long as Casey doesn't try to sleepwalk through his re-election again, he'll probably be okay.
West Virginia (Pure Toss-Up): This is the toughest race to predict, at this point. I could see anything from a Manchin losing by 15 to him winning by 20. Jenkins will be a tough opponent for him, but he is well-established in the state, and even if he bleeds a good deal of his support from 2012, his strong connections to the state will definitely come in handy. The million dollar question is just how much crossover appeal he still has.
Wisconsin (Lean/Likely D): Democrats likely won't get caught flat-footed here like they did in 2016, and Baldwin is the right kind of Democrat for this state. Especially if turnout doesn't drop in Milwaukee like it did last year, Baldwin will definitely be favored.
