With Ohio’s Josh Mandel ending his Senate bid last week, the one Senate race in which the matchup long looked like a foregone conclusion won’t be a rematch of 2012 after all.

The Republican challenger is still unknown in plenty of other races too, with competitive primaries beginning in just four months.

Many of those contests have devolved into loyalty contests to President Donald Trump, with the sparring between the president and his former adviser Steve Bannon complicating some conservative alliances.  

Trump’s involvement in primaries remains unknown, although he signaled over the weekend he’d be more cooperative with leadership than previously thought. He said he’d work to protect incumbents — a shift from last year when he attacked vulnerable GOP senators.

Watch: One Year Out — The 10 Most Vulnerable Senators in 2018

Watching all of this, Democrats are more optimistic about winning the Senate. Their victory in Alabama reduces the number of seats they need to pick up in 2018 to just two.

But just holding their 10 seats in states Trump won remains a tall order.

West Virginia — May 8 (Toss-up)

The first competitive GOP Senate primary is in West Virginia, which Trump carried by 42 points in 2016. The back-and-forth attacks between Attorney General Patrick Morrisey and 3rd District Rep. Evan Jenkins will have been playing out for a year by the time the nominating contest rolls around.

Jenkins has lately been going after Morrisey for his ties to Bannon, while Morrisey continues to swipe at Jenkins for previously being a Democrat and supporting “liberal candidates.”

The Bannon-Trump split could have interesting ramifications in West Virginia. The wealthy Mercer family, which was aligned with Bannon until recently, maxed out to Jenkins last year. That was before Bannon expressed support for Morrisey, which was followed by an endorsement from Great America Alliance.

The former CEO of Massey Energy, Don Blankenship, got out of prison last May and launched his campaign in November. He was convicted on charges of conspiracy to violate safety standards connecting to to a 2010 mine explosion that killed 29 of his employees. His name is likely too toxic to win the nomination, but Republicans are happy to have him spend his own money on TV ads attacking Manchin.

Indiana — May 8 (Toss-up)

Indiana continues to rival West Virginia for the nastiest GOP primary. The member-on-member fighting there has been complicated by the entrance of wealthy businessman Mike Braun. Braun loaned himself $800,000 during the third quarter and was quick to go on the air. The former state representative could shake up the race by writing himself another big check, especially while the member-on-member drama plays out between Reps. Todd Rokita and Luke Messer. But Braun will have to contend with Associated Press revelations that he’s voted as a Democrat. Trump won Indiana by nearly 20 points and it’s the vice president’s home turf, so it’s no surprise all three Republicans are trying to argue they’d be the administration’s best ally.

Ohio — May 8 (Leans Democratic)

Mandel wasn’t without problems, and Republicans might not be upset to land a less gaffe-prone candidate. Wealthy investment banker Mike Gibbons is already in the race and committed to loaning his campaign another $5 million after Mandel dropped out. National Republicans are excited by the idea of GOP Rep. James B. Renacci, who’s running for governor, switching to the Senate race. The congressman has his own money and is close to Trump. Democratic Sen. Sherrod Brown had been gearing up to run against Mandel, but it’s too early to know how the state treasurer’s exit will change the race. There’s not much time for potential GOP candidates. The filing deadline is Feb. 7.

Pennsylvania — May 15 (Leans Democratic)

The GOP primary field has narrowed in recent months, leaving GOP Rep. Lou Barletta and businessman Paul Addis as the top contenders to take on Democratic Sen. Bob Casey.Barletta, who is known for his hard-line immigration stances, could have an edge in a GOP primary as a Trump ally. In October, the president predicted Barletta was “going to win big.” 

Minnesota — June (Likely Democratic)

Newly appointed Sen. Tina Smith will be running in the November special election to fill out the remainder of former Sen. Al Franken’s term.On the GOP side, former Gov. Tim Pawlenty is the candidate many Republicans would like to run because of his name recognition in the state and his fundraising ability. GOP Rep. Tom Emmer could also be a contender. The endorsement will be made at the state GOP convention in early June, and there’s a primary in August to determine ballot access. Republicans will be happy if they just force Democrats to spend a little money here.

California — June 5 (Solid Democratic)

California is hosting the only notable Democratic primary contest against an incumbent so far, with state Sen. Kevin de León taking on longtime Sen. Dianne Feinstein. A handful of other candidates are also running. Under California’s so-called jungle primary system, the top two vote-getters, regardless of party, advance to the general election.

Mississippi — June 5 (Solid Republican)

State Sen. Chris McDaniel has the potential to make this primary interesting if he decides to run against Sen. Roger Wicker. He has said he’ll make a decision about running this month. McDaniel almost defeated Sen. Thad Cochran in a 2014 primary. But running against the former National Republican Senatorial Committee chairman could be a tougher challenge. Trump has lent his support to Wicker. 

Montana — June 5 (Tilts Democratic)

After several higher-profile Republicans passed on the race against Democratic Sen. Jon Tester, the field has been crowded but relatively stagnant. State Auditor Matt Rosendale is still regarded as the candidate to watch and has picked up some conservative endorsements from Great America, the Club for Growth and Sens. Ted Cruz and Mike Lee. Businessman and Air Force veteran Troy Downing is trying to claim the Trump mantle, too, sending out lots of fundraising emails with pictures of himself with the Trump sons. He’s met with the president’s team, The Washington Post reported. But both Rosendale and Downing will have to contend with attacks that they’re from out of state. Russell Fagg, a former district court judge and a state legislator before that, comes from vote-rich Yellowstone County, home to the state’s biggest media outlets.

Nevada — June 12 (Toss-up)

Democrats view Nevada as their top pickup opportunity this year. Sen. Dean Heller is the only Republican up for re-election in a state Hillary Clinton carried in 2016 (she won by 2 points). While Democrats have largely coalesced around Democratic Rep. Jacky Rosen, Republicans could have a potentially bruising primary battle.

Perennial candidate Danny Tarkanian, who has made five unsuccessful runs for office, is challenging Heller. He’s argued he’s the candidate most likely to support Trump’s agenda. Heller’s back-and-forth on health care raised questions about his re-election chances, but he ardently backed the GOP tax overhaul.  

North Dakota — June 12 (Toss-up)

Democratic Sen. Heidi Heitkamp is running for re-election in a state Trump won by roughly 36 points. But it’s still not clear which Republican Heitkamp will face in November.

GOP Rep. Kevin Cramer, who represents the entire state as its at-large representative, recently indicated he was leaning toward jumping in, saying he would decide by the end of January or the beginning of February. Trump has personally pushed Cramer to run.

Other potential GOP contenders have passed on the race, but wealthy state Sen. Tom Campbell is already in on the Republican side.

Tennessee — Aug. 2 (Likely Republican)

Trump won Tennessee by 26 points, and it’s still a reach for Democrats. But after their surprise win in Alabama, they’re not discounting their chances here, especially after landing former Gov. Phil Bredesen. GOP Rep. Marsha Blackburn, whose name recognition makes her the front-runner at this point, raised $2 million and has $4.6 million in the bank. But former Rep. Stephen Fincher wasn’t far behind. He left Congress with a hefty war chest and raised $1.45 million in the fourth quarter. Great America PAC and the Club for Growth have backed Blackburn. 

Michigan — Aug. 7 (Solid Democratic)

The story in Michigan on the Republican side has mostly been about who isn’t running … no Kid Rock, no Rep. Fred Upton, and recently, former state Supreme Court Justice Bob Young dropped out. But Republicans are enthused about John James, an African-American businessman and Iraq war veteran.Even though Trump narrowly won the state in 2016, Michigan is a tough race for Republicans.

Missouri — Aug. 7 (Toss-up)

The Show-Me State is the one race where the general election matchup appears set, though it won’t be the matchup between Democratic Sen. Claire McCaskill and GOP Rep. Ann Wagner that most were expecting last year.

Republicans see Missouri Attorney General Josh Hawley as a top recruit, and Trump already called him “our next senator.” But he could face criticism for running for another office right after he was elected attorney general. 

Hawley had $782,000 at the end of September. He hasn’t released his latest numbers. McCaskill announced Monday she raised nearly $2.9 million in the fourth quarter and broke state fundraising records by raking in nearly $12 million in 2017. Her campaign said she heads into 2018 with roughly $9 million.

Wisconsin — Aug. 14 (Tilts Democratic)

Trump won the Badger State by less than a point in 2016. Democratic Sen. Tammy Baldwin has pushed her positions on bolstering American manufacturing. But Republicans will likely attempt to paint her as too liberal. 

State Sen. Leah Vukmir and Marine veteran (and former Democrat) Kevin Nicholson are facing off for the Republican nomination.

Both of them have big-dollar donors behind them and various outside groups on their side. The Associated Press reported that Nicholson outraised Vukmir 2-to-1 in the fourth fundraising quarter of 2017, raising $800,000 to Vukmir’s $400,000. Businessman Eric Hovde, who ran unsuccessfully for Senate in 2012, is still considering jumping in the race.

Arizona — Aug. 28 (Toss-up)

Former state Sen. Kelli Ward was already in the race before GOP Sen. Jeff Flake announced his retirement. She earned Bannon’s backing, but has distanced herself from him since Trump denounced his former adviser. 

GOP Rep. Martha McSally has told her fellow Arizona Republicans that she plans to run for Senate, but has yet to officially announce her campaign. She is already facing pushback from the Club for Growth PAC, which has said it would oppose her candidacy if she runs. Senate Majority Leader Mitch McConnell has listed her among the top GOP challengers of the cycle.

Whoever wins the primary will likely face Democratic Rep. Kyrsten Sinema. 

Florida — Aug. 28 (Tilts Democratic)

With Trump’s encouragement, Gov. Rick Scott is widely expected to run. If he doesn’t, it’ll be a mad dash from the late Aug. 28 primary until the general election. As a statewide officeholder, Scott gets plenty of earned media — both good and bad. But for now, Democratic Sen. Bill Nelson has the Senate race to himself. He had $6.3 million in the bank at the end of the third quarter, but he’s been slow to staff up.