MADISON, Wis. (AP) — Wisconsin Republicans are increasingly picking sides in the U.S. Senate primary fight pitting a former Marine and Democrat who casts himself as a political outsider against a longtime elected official with deep ties to Gov. Scott Walker.
Both candidates are also scrambling to show allegiance to President Donald Trump, but the race has not turned into a referendum on Trump or a battle over the ideological future of the party like last month's GOP runoff in Alabama.
Neither Trump nor Walker have publicly engaged in the state's Senate race while the two announced Republican candidates struggle — mostly in private — to win over wealthy donors and influential insiders 10 months before the primary.
And the field may grow, with at least one more Republican still mulling a bid.
On Monday, a new super PAC headed by a former Walker campaign manager that includes other former Walker operatives launched in support of state Sen. Leah Vukmir. Her GOP Senate primary opponent, political newcomer Kevin Nicholson, has also gathered former Walker donors to his side.
The winner will take on Sen. Tammy Baldwin, who is facing re-election for the first time and stands as the last remaining Democratic state office holder of significance in Wisconsin. Knocking out Baldwin would complete the transition of Wisconsin from a blue to red state that began with Walker's first election victory in 2010 and continued last year with Trump's narrow win.
Vukmir is well-known to Wisconsin Republicans, given her 15 years in the Legislature. Nicholson, who was head of the College Democrats of America in 2000, is highlighting his years of service in the Marines while easing concerns about his Democratic past and trying to capture Trump voters who favor outsider candidates. His campaign slogan is "Send in the Marine" and his website prominently brands him as a "Marine. Outsider. Conservative."
Nicholson convinced at least one important voter.
Richard Uihlein, who founded shipping and packing materials company Uline Corp. and is a Republican mega-donor, gave Nicholson his much-sought after stamp of approval with a $3.5 million donation to a supportive political action committee. He also gave $1.5 million to the PAC for the national conservative group Club for Growth, which endorsed Nicholson in August before Vukmir entered the race.
Both Uihlein and Club for Growth have been strong Walker supporters.
Vukmir initially backed Walker and then Florida Sen. Marco Rubio in the 2016 presidential race. But she's not ceding the Trump voter to Nicholson. She wears a "Make America Great Again" hat on her Facebook page and has posted supportive messages of Trump on social media.
Polls now show a strong majority of Wisconsin Republicans support Trump, but that wasn't always the case. He lost the primary and many state Republicans either initially backed Walker or others in the GOP field.
That has helped create the Senate race dynamic where allegiance to Trump has not been a litmus test, said Charles Franklin, a political science professor who is lead pollster for Marquette University.
"The campaign at this point is a division between conservative factions of the Republican Party and its allied group and backers with money, rather than the kind of division we saw in Alabama," he said, referencing last month's Trump-focused Senate runoff election in that state.
Vukmir was first elected in 2002, taking the suburban Milwaukee Assembly seat previously held by Walker. She's been a fierce Walker ally, including in 2011 when as a new member of the state Senate she voted for the law known as Act 10 that took away collective bargaining rights from public workers.
Vukmir won the endorsement of Michael Grebe, the political godfather of both Walker and House Speaker Paul Ryan, who retired a year ago as head of the influential conservative Lynde and Harry Bradley Foundation. Grebe served as chairman of Walker's gubernatorial campaign in 2010 and his failed 2016 presidential bid.
Vukmir is also endorsed by Diane Hendricks, the billionaire owner of roofing supply company ABC Supply who gave $5 million in 2015 to a PAC supporting Walker's presidential run and has been a heavy contributor to his three previous gubernatorial campaigns.
Walker, who typically stays out of Republican primaries, plans to remain neutral in the Senate race, said his campaign manager, Joe Fadness.
The field could still change before the August primary — millionaire businessman Eric Hovde is considering whether to jump in after his second-place finish in the Republican primary in 2012. And U.S. Rep. Sean Duffy, an early and prominent Trump backer who said in February he would not run for Senate, continues to be talked about as a possible late-addition to the race. Duffy's chief of staff Pete Meachum said Monday that Duffy's mind had not changed.
One of Duffy's closest political allies and mentors — northern Wisconsin businessman and former state Republican Party finance chairman Bill Johnson, Jr. — isn't waiting for a change of heart. He endorsed Vukmir.
Follow Scott Bauer on Twitter at https://twitter.com/sbauerAP