ST. PAUL — In ads, rallies and the signage on his campaign bus, the Republican running for Minnesota attorney general has a prevailing message for voters: He’s not Keith Ellison.

As the Democratic congressman struggles to survive the cloud of a former girlfriend’s assault allegation, GOP foe Doug Wardlow is amplifying that claim in hopes of breaking Democrats’ half-century hold on the office. A new poll this week from the Star Tribune and Minnesota Public Radio showed Wardlow, a virtual unknown a few months ago, with a slight lead over Ellison, the deputy chairman of the Democratic National Committee.

In Wardlow’s first ad, a narrator spent the first 20 seconds of a 30-second spot focused on Ellison. It shows images of the congressman in a shirt that reads, “I don’t believe in borders” in Spanish, and in reference to the abuse allegation, asks: “How can we trust him to look out for us?” The back of Wardlow’s campaign bus is brandished with the words, “Stop Keith Ellison,” in all capital letters.

“Minnesotans are very concerned about those allegations, because they’re very credible,” Wardlow said. “Keith Ellison is unfit to be the state’s top law enforcement official.”

Ellison has denied the allegation, pointing to a report commissioned by Democratic leaders that found it “unsubstantiated.” Wardlow called that report a whitewash, noting the attorney who performed it was connected to the state party.

The outcome of the race has implications beyond Minnesota. Ellison has vowed to follow the path of Democratic attorneys general in other states who have challenged President Donald Trump’s policies on immigration and other issues. A loss would take that off the table and could effectively end the political career of a liberal who was the first Muslim elected to Congress.

Wardlow has portrayed himself as an apolitical alternative to Ellison, playing up his experience in international trade law and eminent domain cases. He has laid out a sober roadmap for the attorney general’s office: boosting assistance to county attorneys on criminal cases, cracking down on opioid abuse and fighting human trafficking.

Democrats and allied groups say Wardlow is concealing a conservative past that is far more activist.

They note his years as a top attorney for Alliance Defending Freedom, a Christian nonprofit group, leading its fight against the U.S. Supreme Court case that eventually legalized same-sex marriage in 2015. Before Wardlow left ADF last year to start his campaign, he also fought against letting transgender students use bathrooms that match their gender identity and defended a Michigan business that fired a transgender employee, arguing the business shouldn’t be forced to violate its religious beliefs.

Wardlow handed Democrats a gift late in the campaign when he was recorded at a private fundraiser saying he would “fire 42 Democratic attorneys right off the bat and get Republican attorneys in there.”

In one term as a suburban state legislator, Wardlow sponsored so-called “right-to-work” legislation that would block unions from collecting mandatory dues and tried to block the state from setting up a health insurance exchange after the passage of the Affordable Care Act. He lost his re-election bid in 2012.

Monica Meyer, executive director for the gay and transgender rights advocacy group OutFront Minnesota, said Wardlow’s past should be disqualifying.

“He would be the top lawyer for our state … and he worked to dismantle all of our legal protections. For us, that’s just so troubling,” Meyer said.

Wardlow said he misspoke in his remarks about firing Democrats, meaning simply that if elected he would interview existing staff attorneys and new prospects “to ensure they are people I can trust to put the rule of law over politics.”

He said his career has been built on protecting constitutional rights to freedom of speech and religion, and voters shouldn’t look to his past as guidance for what he would do as attorney general.

“I always diligently fought for the rights of my clients. There’s nothing political about it,” Wardlow said. “(Ellison) is just a very political figure, No. 2 at the DNC. It doesn’t get much more political than that.”

Ellison doesn’t deny he’s political. But he accuses Wardlow of trying to ignore his own background to keep the race focused on the claim by Ellison’s former girlfriend, Karen Monahan, that he dragged her off a bed in 2016.

“I’ve been clear about who I am. I’ve never said I’m this apolitical person with no views on anything, which is what he’s trying to do,” Ellison said in an interview.

As voters weigh the allegation against Ellison with what they’re learning about Wardlow, a third candidate in the race has thrown his support to Ellison.

Noah Johnson, running for attorney general on a campaign to legalize marijuana, urged his supporters to vote for Ellison after Ellison said he too supports legalization. But Johnson referenced Wardlow’s remarks about firing Democrats, too.

“In a perfect world, we would not have to talk about a mainstream political candidate who’s so far to the right that he has to pretend to be “apolitical” in his campaign,” Johnson said.