The 2018 fight for the Senate majority has only just begun, with still not a single retirement on the books and nearly every battleground lacking a major challenger.
What’s clear at the end of the first fundraising quarter is that Senate Democrats face a daunting map—10 Democrats are up in states President Trump won, and just one Republican is up in a Hillary Clinton state.
What’s unknown is just how much the political environment in a midterm under Trump benefits Democrats. That variable ensures fluidity in the landscape and means Hotline’s first Power Rankings of the cycle, which are primarily based on the strength of the incumbents and the fundamentals of the states, merely set the baseline for the remaining 19 months.
The sheer number of Democratic senators up for reelection (25 out of 34 seats) means these rankings predominantly feature the party's incumbents.
But a factor to watch in the coming months as Republicans aim to expand their majority is how the president’s dangerously low approval ratings affect candidate recruitment. That could, for instance, knock down a Democratic-held seat in a state like Pennsylvania and push Republican-held Arizona firmly into the top 10.
It could also help Democrats limit their losses in a heavily tilted cycle.
1. Indiana — Sen. Joe Donnelly (D)
Republicans may be headed for a contentious primary between two likely candidates, Reps. Todd Rokita and Luke Messer. No matter the outcome, Donnelly faces a steep climb in a state Trump won by 19 points. Even Democrats concede that his 2012 win was fueled in large part by a flawed opponent, and Republicans are certain they will field a far stronger nominee. Also hanging over the race is Democrats’ embarrassing defeat in the Senate race last year, but the party insists that the moderate Donnelly boasts far more blue-collar appeal than Evan Bayh.
2. Missouri — Sen. Claire McCaskill (D)
McCaskill has already declared herself the underdog. Trump improved by 10 points on Mitt Romney’s winning margin, as Republicans knocked Democrats out of four statewide offices. But Democrats point to Missouri’s independent streak, after Jason Kander came within 3 points of unseating Sen. Roy Blunt last cycle. Like Donnelly, McCaskill benefited in her last race from a highly controversial opponent. This time, Republican Reps. Ann Wagner and Vicky Hartzler are possible McCaskill challengers, in addition to newly elected state Attorney General Josh Hawley.
3. North Dakota — Sen. Heidi Heitkamp (D)
Democrats held all three federal seats in the state until 2010, and Heitkamp’s decision to run for Senate in 2012 ultimately saved the party from a Republican sweep. This seat would be incredibly difficult for Democrats to hold if Heitkamp decides to retire, a decision that she told the Fargo newspaper won’t come until this summer. But if she seeks reelection, after running 11 points ahead of President Obama her first time out, it will make picking up this seat far more difficult for Republicans than Trump’s 36-point victory in the state would indicate. Rep. Kevin Cramer has said he has Trump’s support should he decide to run.
4. Nevada — Sen. Dean Heller (R)
Heller is Democrats’ top target, one cycle after the party carried Nevada at the presidential level, held an open Senate seat, and flipped two House seats. Heller was narrowly elected to a full term in 2012, and Democrats still privately grouse that he would have lost if not for their ethics-challenged nominee. But Democrats, who suggest Heller will be caught between the competing demands of his base and moderate GOP voters, lack an obvious challenger. Former state Treasurer Kate Marshall and state Senate Majority Leader Aaron Ford are among the names floated.
5. West Virginia — Sen. Joe Manchin (D)
Few senators would enter an election cycle in a state that the opposing party’s presidential nominee carried by 42 points and stand any chance of winning again. But this Democrat, who turns 70 in August and has held statewide office since 2000, is the exception to that rule. Manchin has gone out of his way since November to make it clear he is open to working with Trump, but he also firmly opposed Trump’s plan to repeal Obamacare. Republicans have already tied Manchin to Hillary Clinton in a digital ad, and the National Republican Senatorial Committee has met with Rep. Evan Jenkins and state Attorney General Patrick Morrisey about taking on the former governor.
6. Florida — Sen. Bill Nelson (D)
The greatest hurdles for any Sunshine State candidate challenging a Senate incumbent are money and name ID. Those disappear if Republican Gov. Rick Scott takes on Nelson, who was reelected in the strong Democratic year of 2006 with 60 percent and in the more neutral environment of 2012 with 55 percent. Scott, one of Trump’s earliest backers, can easily be tied to the president, who likely lifts Nelson’s prospects despite winning Florida narrowly in November. Nelson led Scott by 5 or 6 points in four polls released just this month.
7. Montana — Sen. Jon Tester (D)
Tester may have caught his luckiest break with Republican Rep. Ryan Zinke choosing to join Trump’s Cabinet. But there remain a number of Republicans, including state Attorney General Tim Fox and state Auditor Matt Rosendale, who could mount viable campaigns in a state that Trump carried by more than 20 points. Still, Tester, the most recent chair of the Democratic Senatorial Campaign Committee, enjoys a strong brand in his home state and has two extraordinarily tough races under his belt. Democratic Gov. Steve Bullock’s reelection in November offers additional proof that the party can still run successfully statewide.
8. Ohio — Sen. Sherrod Brown (D)
In some ways, the 2012 race never ended. Josh Mandel, the Republican state treasurer, who came up 6 points short against Brown last time, waited less than a month after the 2016 elections to enter the race. Democrats have pounced on Mandel's use of a state-funded marketing campaign as part of its narrative that he is an ambitious politician more focused on his next job than his current one. The open-seat governor race, and backing from Sens. Marco Rubio and Tom Cotton, helps keep Mandel’s primary opponents to a minimum, but Rep. Pat Tiberi is still considering it.
9. Wisconsin — Sen. Tammy Baldwin (D)
A crowded GOP primary once again appears likely in this traditionally Democratic state that narrowly swung for Trump. Rep. Sean Duffy is out, but several other Republicans may be in, including businessmen Kevin Nicholson and Eric Hovde, who lost in the 2012 primary. GOP strategists hoped to avoid a replay of six years ago, but they are emboldened by two recently successful midterm elections, plus Republican Sen. Ron Johnson’s come-from-behind victory last year. Republicans are already attacking Baldwin on the Tomah VA crisis and casting her as a clone of Sen. Elizabeth Warren.
10. Pennsylvania — Sen. Robert Casey (D)
With no one likely to replicate the road maps that Trump and Sen. Pat Toomey used in their narrow victories last year, Pennsylvania Republicans likely need a candidate who can combine the two. Former Trump delegate Andrew Shecktor and state Rep. Rick Saccone, a fellow Trump loyalist, have already declared campaigns, but national Republicans are likely to keep recruiting here. Meanwhile, Casey has emerged as an outspoken force against Trump, readily aligning with his base on fights over the Supreme Court and Obamacare.