Former Trump campaign adviser George Papadopoulos, center, arrives at a closed-door hearing before the House Judiciary and Oversight Committee on Thursday. (Carolyn Kaster/AP)

One of President Trump’s top allies on Capitol Hill is calling for members of the FBI and Justice Department to be referred for potential disciplinary action over their scrutiny of former Trump campaign adviser George Papadopoulos, alleging — without evidence — that his constitutional rights may have been violated by federal law enforcement officials.

“Not only was there no collusion but there was not even the opportunity for collusion based on his contacts” with alleged Russian intermediaries, said Rep. Mark Meadows (R-N.C.), recounting what Papadopoulos told lawmakers during a seven-hour, closed-door interview Thursday with members of the House Judiciary and Oversight and Government Reform committees.

The joint panel is investigating federal law enforcement’s conduct during the investigations of Trump’s campaign and Hillary Clinton’s use of private email server. Over the course of that probe, the president’s congressional allies have accused several FBI and Justice Department officials of anti-Trump bias and other wrongdoing, in what Democrats call a thinly-veiled effort to undermine the origins of special counsel Robert S. Mueller III’s investigation of Russian interference in the 2016 presidential election.

On Thursday, Meadows made one of the most direct accusations yet — accusing federal law enforcement officials of acting unconstitutionally by investigating Papadopoulos.

“I am very troubled that his fourth amendment rights may have been violated and the way that this was conducted was inappropriate” Meadows added. He said he would recommend that an unspecified number of officers be referred to the Justice Department’s Office of Professional Responsibility, though he declined to identify them.

Meadows and other Republicans on the panel have taken aim at current and former FBI and Justice Department officials previously, alleging wrongdoing or other bias in their handling of the Trump-Russia probe.

Papadopoulos played an early and pivotal role in prompting that investigation, when he told an Australian diplomat in the United Kingdom that he knew Russia had thousands of Clinton’s emails, weeks before that information was public. Papadopoulos also suggested that he use his contacts to reach out to Russia on behalf of the Trump campaign — and that Trump “nodded with approval,” according to Papadopoulos’s lawyer.

Papadopoulos was convicted in September of lying to the FBI, though he has yet to serve the two-week sentence he received. Democrats also dismissed Papadopoulos’s testimony as untrustworthy.

“I see this whole thing as a footnote to a sideshow of a wild-goose chase,” said Rep. Jamie B. Raskin (D-Md.), adding that one must “take his testimony for what it’s worth” — intimating it was worth quite little.

But Republicans said they found Papadopoulos to be “very forthcoming” and credible, noting that he offered to share all his communications, including emails and text messages, with the committees.

Meadows and Rep. John Ratcliffe (R-Tex.) emphasized that Papadopoulos said he “never knowingly” met with a Russian government official — though they acknowledged he may have done so unknowingly. They also insisted Papadopoulos’s involvement in Trump’s campaign was “limited.”

“We continue to question why the FBI and the Department of Justice felt that there was probable cause in looking at figures like George Papadopoulos and Carter Page, who had either minimal or nonexistent contacts with the Russian government,” Ratcliffe said.

Page, also a former adviser to the Trump campaign, has said he once worked as an informal adviser to the Kremlin. Still, Meadows and other Republicans have seized on the FBI’s application to surveil Page, calling it flawed, incomplete and biased.

Recently, Trump’s allies on Capitol Hill have sought to demonstrate that the FBI ignored information Papadopoulos gave them that might have removed suspicion from Page. They refused to detail more about those concerns Thursday.

Papadopoulos has claimed in recent days that he was “set up” by the FBI to be “a patsy for a ‘Russia’ conspiracy.” While Meadows and other Republicans did not echo Papadopoulos’s language, their suggestion that FBI officials may have infringed on his constitutional rights in effect buttresses those claims.

Papadopoulos has accused Alexander Downer, the Australian diplomat, of conspiring with former director of national intelligence James R. Clapper Jr. to hide what Papadopoulos charged was “the most profound, and illegal, spying operation against an American and the presidential campaign he worked for in history.” Meadows said that during Thursday’s interview, Papadopoulos indicated he had been in contact with two other government officials, but would not say whether they were American or foreign.

In a letter to the committees earlier this week, Papadopoulos’s lawyer said he would be willing to discuss his interactions with nine individuals, including Downer, Stephen Halper, a professor who worked as an FBI source and had contacts with Papadopoulos, and Joseph Mifsud, a London-based professor who told him in April 2016 that the Russians had thousands of Clinton’s emails.

Exiting the interview, Papadopoulos told reporters that he was “very happy with how it went.” He declined to elaborate.