A Republican primary is officially underway in the Wisconsin Senate race, with candidates facing off over who should take on Democratic Sen. Tammy Baldwin next year.

President Donald Trump won the Badger State by less than one point in November, the first time a Republican presidential nominee had won Wisconsin in more than 30 years. GOP Sen. Ron Johnson also ran 2 points ahead of Trump in winning a second term.

So Republicans are targeting Baldwin, one of 10 Senate Democrats up for re-election in states that Trump won. Wisconsin, they say, is shifting to the right.

Two Republicans have jumped into the race, with another eyeing a run. A key question facing Wisconsin Republicans is whether a contested primary could help the eventual nominee by testing his or her campaign, or whether a battered candidate could emerge with even less money for the general election.

“The biggest concern is resources,” Wisconsin GOP Rep. Sean P. Duffy said. “Money’s not going to be a problem in this race.”

Duffy decided in February that he wouldn’t run for Senate. Even though he is still being encouraged to jump into the race, he said he is definitely not changing his mind. 

With Duffy forgoing a run, other candidates have jumped in.

Marine veteran Kevin Nicholson, a Democrat-turned-Republican, launched his campaign in July. He has already received the endorsement of the conservative Club for Growth PAC.

Last week, state Sen. Leah Vukmir jumped into the race, saying in a campaign video that the Senate needs a “proven, consistent conservative.” The state Senate majority leader, Scott Fitzgerald, announced Monday that he would not be running for Senate and instead would back Vukmir. In a thinly veiled slight to Nicholson, Fitzgerald said Vukmir is “an actual conservative.”

Vukmir and Nicholson had been trading barbs over who is more conservative even before Vukmir officially launched her campaign.

Wisconsin Republicans are also watching Eric Hovde, a wealthy businessman who ran for Senate in 2012 but lost in the GOP primary to former Gov. Tommy Thompson. Two state GOP strategists said Hovde’s name recognition from that race and his ability to self-fund would make him a strong contender.

Fundraising numbers available in October could influence Hovde’s decision to run or not, one strategist said. Nicholson and Vukmir both have influential financial backers. Diane Hendricks, a reported billionaire who supported GOP Gov. Scott Walker, is co-chairing Vukmir’s finance committee. Nicholson has support from a super PAC being funded by a different billionaire, Richard Uihlein.

Democrats are content to watch Republicans fight it out among themselves as Baldwin emphasizes her work in the Senate. They also see some similarities to her 2012 race. Baldwin was on her own on the Democratic side, while Republicans had a primary. Thompson entered the GOP primary as a top contender and eventually won, but some Wisconsin Republicans said the battle weakened him for the general election, which he lost.