A Republican senator demanded in a letter on Wednesday that ABC News turn over any correspondence it may have had with the Kamala Harris campaign ahead of last week's debate, alleging there was a clear bias on display against former President Trump.

"On debate night, it became abundantly clear that ABC News and its respective moderators had a biased agenda," Sen. Roger Marshall, R-Kansas, wrote to ABC News President ​​Almin Karamehmedovic and Harris’ campaign manager, Julie Chávez Rodriguez, in a letter obtained by Fox News Digital.

The letter was first reported by NewsNation.

Marshall said there was a "three-on-one" onslaught against Trump, echoing the Republican's complaints about the debate moderated by ABC's David Muir and Linsey Davis.

The debate, which political pundits widely called a victory for Harris, featured five fact-checks of Trump in real time by the moderators, while Harris was never fact-checked on any of her remarks.

VOTERS GIVE HARRIS THE DEBATE WIN, BUT PRAISE TRUMP ON POLICY: SHE GOT UNDER HIS SKIN

Roger Marshall

Kansas Sen. Roger Marshall wrote a letter to ABC News demanding proof it hadn't coordinated ahead of time with the Kamala Harris campaign. (Getty Images)

"Recent reporting has suggested the possibility that the Harris campaign may have inappropriately influenced the proceedings to benefit Vice President Harris and undermine President Trump," he wrote. "If these and other allegations are true, the impartiality of the mainstream media will continue to be questioned by the American people."

Marshall's letter wants the media organization to turn over and also publicly release any texts and emails to dispel any concerns about advance coordination.

The letter cited accusations of bias against Muir, Davis and ABC before and during the debate. Marshall also cited polling showing widespread public distrust in the mainstream press, and he noted the friendship with Harris of top Disney executive Dana Walden, who has made donations to Harris and numerous other Democratic candidates.

"The American people deserve transparency and accountability from the mainstream media and a full accounting of whether ABC News coordinated with the Harris campaign to skew the debate’s questions and fact-checking in favor of the Vice President," he wrote.

The letter, which cannot compel ABC News to turn over any documents, added it wanted a response by Sept. 27.

ABC News didn't respond to a request for comment.

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Trump, who claimed victory in the debate but has taken criticism for an uneven performance, suggested during a rally in Las Vegas last week that Harris had obtained the questions ahead of time.

"I hear she got the questions, and I also heard she had something in the ear," Trump said, suggesting without evidence she wore an earpiece.

Trump ally Sen. Tom Cotton, R-Ark., erupted on ABC this week for not correcting Harris' false remark at the debate that there was not "one member of the United States military who is in active duty" in a combat or war zone anywhere.

"This goes beyond bias--it's a media company effectively joining the Harris campaign," he wrote on X.

TRUMP-HARRIS

Vice President Kamala Harris and former President Donald Trump during the second presidential debate at the Pennsylvania Convention Center in Philadelphia, Pennsylvania, on Tuesday, Sept. 10, 2024. (Getty Images)

ABC'S LINSEY DAVIS ADMITS FACT-CHECKING OF TRUMP WAS BECAUSE CNN LET HIS STATEMENTS 'HANG' AT FIRST DEBATE

ABC's Martha Raddatz, a network colleague of Muir and Davis, said Sunday that fact-checkers "found that to be false."

"There are currently 900 U.S. military personnel in Syria, 2,500 U.S. troops in Iraq. All have been under regular threat from drones and missiles for months," she said. "We also have action in the Red Sea. Also, every single day, the Navy SEALs, Delta Forces special operators can be part of any sort of deadly raid." 

Muir, who anchors "World News Tonight" for ABC, addressed the debate and the aftermath in an interview Monday on "Live With Kelly and Mark."

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"All of the noise that you hear afterward about you know, ‘Which candidate won the debate, did the moderators win or lose?’ That's just noise. You all know that. The most important thing to remember is you all have the power," he told the audience. 

The Trump and Harris campaigns didn't return requests for comment.