President Trump said Thursday that he won't allow former White House counsel Don McGahn to testify before Congress.

"I don't think I can let him and then tell everybody else you can because especially him because he was the counsel," Trump said during a clip of a 20-minute interview aired on Fox News.

Rep. Jerry Nadler, D-N.Y., chairman of the House Judiciary Committee, last week issued a subpoena to McGahn to testify before the committee. Senate Democrats have also indicated that they want McGahn to testify before Congress as Democrats on Capitol Hill seek to follow up on Mueller's investigation into Russia's interference in the 2016 presidential race, an investigation that widened to include an inquiry into possible obstruction of justice by Trump.

Trump's comments come a day after Attorney General William Barr testified before the Senate Judiciary Committee, and the same day Barr refused to testify before the House Judiciary Committee.

More:Attorney General William Barr refuses to testify at House hearing about special counsel Robert Mueller

According to Mueller's report, the president ordered McGahn to have the special counsel removed in mid-2017. McGahn refused and later told another White House aide that the president asked him to "do crazy s---." McGahn also told investigators that the president had asked him to deny having been asked to fire Mueller.

Barr, in a summary of Mueller's report, said he and the deputy attorney general concluded that Trump's actions did not constitute obstruction of justice. Barr, who on Wednesday testified on Capitol Hill, stood by his summary of the Russia probe report, despite Mueller's recently revealed rebuke of the attorney general's characterization on the issue of obstruction of justice.

Trump has hinted that he intended to block aides — both current and former — from testifying before Congress, saying last month that the White House was looking into invoking executive privilege to block such testimony.

In an interview with the Washington Post last month, Trump said the investigations led by Democrats in the House are unnecessary given the results of Mueller's report.

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"There is no reason to go any further, and especially in Congress where it’s very partisan — obviously very partisan," Trump told the Post. "I don’t want people testifying to a party, because that is what they’re doing if they do this."

He told the Post that the White House Counsel’s Office was seriously debating asserting executive privilege, which it did not do with information compiled in Mueller's report, to block congressional testimony. Trump said White House lawyers had yet to make a "final, final decision.”

The Post had reported that the White House was specifically looking into asserting privilege to block McGahn’s testimony, as he was one of the star witnesses for Mueller’s investigation and outlined some of the most damning, behind-the-scenes episodes at the White House.

More:Trump: White House considering asserting executive privilege to hinder congressional probes

Trump maintained that there is no need to investigate further now after Mueller's report.

"I would say it's done," the president said Thursday in the Fox News sit-down. "Nobody has ever done what I've done, I've given total transparency. It's never happened before like this.

"Congress shouldn't be looking anymore. It's done," he said.

Contributing: Christal Hayes