Wesley Bell, a St. Louis prosecutor who is mounting a formidable Democratic primary challenge against Rep. Cori Bush (D-Mo.), is campaigning as someone who will produce more tangible results for the district while sharing many of her same left-leaning values.

But one line on Bell’s political resume is at odds with his promise to champion a progressive agenda. In 2006, Bell managed the campaign of a conservative Republican running for the same seat Bell is seeking today.

The candidate, Mark J. Byrne, ran as a fierce abortion opponent and gun rights crusader. “I intend to protect the rights of the unborn,” his campaign website read. “I believe that there is no greater job for elected representatives.”

He ultimately lost to incumbent Rep. William Lacy Clay Jr., who remained in office until Bush successfully challenged him in 2020.

“Nearly 20 years ago, Wesley helped a longtime friend by volunteering with his campaign, in spite of their differences in political affiliations and positions on many issues,” said Anjan Mukherjee, a spokesperson for Bell’s campaign. “Wesley has been a progressive prosecutor, working to overturn wrongful convictions and refusing to prosecute women for abortions, and he will be a progressive member of Congress who works with President Biden.”

Byrne, who is now a municipal judge in a neighboring county, said Bell ran his campaign as a friendly favor. The two met as young lawyers in St. Louis County, he recalled, and became friends over years of poker nights.

“He didn’t run a Republican’s campaign, he ran a friend’s campaign,” Byrne said in an interview this week with HuffPost. “He and I didn’t see eye to eye on political issues, but he did the best that he could to try to help me get elected.”

Bell has avoided any mention of the Byrne campaign as he crisscrosses Missouri’s bright-blue 1st Congressional District, which includes St. Louis and Ferguson, the birthplace of the Black Lives Matter movement in 2014.

Bush and Bell both emerged from the Ferguson uprising as political leaders. And the primary has mostly revolved around their dueling claims to better represent progressive voters. In her four years in Congress, Bush, a former nurse, rallied national support for a COVID-era eviction moratorium and led the first calls for a cease-fire in the ongoing fighting in Gaza. Bell, claiming Bush gets better headlines than results, is campaigning on his record as the St. Louis County prosecutor, a role in which he pursued alternatives to incarceration for people convicted of minor offenses.

Supporters of Bush argue Bell is not a genuine progressive but the Democrat preferred by Republicans.

“Bell’s willingness to defend abortion rights depends solely on how it helps his own political career,” said Usamah Andrabi, the spokesperson for Justice Democrats, a grassroots group supporting Bush. “There is no excuse that can justify leading the campaign to elect a Republican extremist.”

As of May, Bell has raised more than $65,000 in contributions from donors who normally give to Republicans. They include a former GOP speaker of the Missouri House, the billionaire hedge fund founder Daniel Loeb, and the former finance chair for Sen. Tim Scott’s (R-S.C.) presidential super PAC.

At the end of the last fundraising quarter, Bell reported having about twice as much cash on hand as Bush.

Bell has also benefited from more than $300,000 in ads paid for by the American Israel Public Affairs Committee’s super PAC. While AIPAC backs candidates of both parties who support U.S. military assistance for Israel, progressive critics have noted the PAC’s top contributors are GOP megadonors. Bush is one of AIPAC’s top targets in the 2024 elections.

“The fact that my ‘Democratic’ opponent’s entrance into politics was managing a Republican congressional campaign for a far-right, anti-abortion extremist is strikingly consistent, and it should tell voters everything they need to know,” Bush said in a statement. “He can’t be trusted to protect our reproductive freedoms and abortion rights, secure our democracy, and stand up to the MAGA Republican extremists in Congress.”

Bell’s 2006 stint as a GOP campaign hand fell during a historic wave year for Democrats. Amid deepening anger over President George W. Bush’s mishandling of the war in Iraq and Hurricane Katrina and a drumbeat of Republican scandals, Democrats easily recaptured the House and Senate.

Byrne, the candidate Bell worked for, epitomized the kind of staunch conservative voters rejected.

“I am pro-life and I will support a constitutional amendment to protect the rights of the unborn,” Byrne told the St. Louis Post-Dispatch. “I will protect our Second Amendment right to bear arms. … I will increase funding for the border patrol and crack down on employers who knowingly hire illegal immigrants.”

When the Post-Dispatch editorial board supported his more moderate primary rival, Byrne’s campaign spun it as a “wonderful endorsement” of his “strongly conservative positions.”

“The Post is correct,” his campaign website read. “While some may waver on their positions, Mark will not compromise his integrity just to become the ‘moderate’ candidate.”

Byrne won the primary. But as a first-time political candidate in a Democratic stronghold, he proved a weak match for Clay, whose father had held the same congressional seat for 32 years before him.

Byrne now denies he ran a right-wing conservative campaign, and argues that Bell’s role in his congressional bid shouldn’t hurt his own political future.

“In all the conversations that I have ever had with Wesley, he’s not a Republican, he doesn’t think like a Republican or have a Republican agenda,” Byrne said. “He’s always been a lifelong Democrat.”

But Megan Green, the president of the St. Louis Board of Aldermen who is supporting Bush for reelection, isn’t reassured.

“It is a little strange to me that this is where you’d be putting your efforts in 2006, when there were a good number of Democrats running for office that needed help and support,” she said. “Friendship is one thing. But empowering friends who have problematic viewpoints to get into positions of power, that’s concerning.”