WASHINGTON -- Disputing U.S. President Donald Trump's persistent, baseless claims, Attorney General William Barr declared the U.S. Justice Department has uncovered no evidence of widespread voter fraud that could change the outcome of the 2020 election.

Barr's comments, in an interview Tuesday with the The Associated Press, contradict the concerted effort by Trump, his boss, to subvert the results of last month's voting and block President-elect Joe Biden from taking his place in the White House.

Barr told the AP that U.S. attorneys and FBI agents have been working to follow up specific complaints and information they've received, but "to date, we have not seen fraud on a scale that could have effected a different outcome in the election."

The comments, which drew immediate criticism from Trump attorneys, were especially notable coming from Barr, who has been one of the president's most ardent allies. Before the election, he had repeatedly raised the notion that mail-in voting could be especially vulnerable to fraud during the coronavirus pandemic as Americans feared going to polls and instead chose to vote by mail.

More to Trump's liking, Barr revealed in the AP interview that in October he had appointed U.S. Attorney John Durham as a special counsel, giving the prosecutor the authority to continue to investigate the origins of the Trump-Russia probe after Biden takes over and making it difficult to fire him. Biden hasn't said what he might do with the investigation, and his transition team didn't comment Tuesday.

Trump has long railed against the investigation into whether his 2016 campaign was co-ordinating with Russia, but he and Republican allies had hoped the results would be delivered before the 2020 election and would help sway voters. So far, there has been only one criminal case, a guilty plea from a former FBI lawyer to a single false statement charge.

Under federal regulations, a special counsel can be fired only by the attorney general and for specific reasons such as misconduct, dereliction of duty or conflict of interest. An attorney general must document such reasons in writing.

Barr went to the White House Tuesday for a previously scheduled meeting that lasted about three hours.

Trump didn't directly comment on the attorney general's remarks on the election. But his personal attorney Rudy Giuliani and his political campaign issued a scathing statement claiming that, "with all due respect to the Attorney General, there hasn't been any semblance" of an investigation into the president's complaints.

Other administration officials who have come out forcefully against Trump's allegations of voter-fraud evidence have been fired. But it's not clear whether Barr might suffer the same fate. He maintains a lofty position with Trump, and despite their differences the two see eye-to-eye on quite a lot.

Still, Senate Democratic leader Chuck Schumer quipped: "I guess he's the next one to be fired."

Last month, Barr issued a directive to U.S. attorneys across the country allowing them to pursue any "substantial allegations" of voting irregularities before the 2020 presidential election was certified, despite no evidence at that time of widespread fraud.

That memorandum gave prosecutors the ability to go around longstanding Justice Department policy that normally would prohibit such overt actions before the election was certified. Soon after it was issued, the department's top elections crime official announced he would step aside from that position because of the memo.

The Trump campaign team led by Giuliani has been alleging a widespread conspiracy by Democrats to dump millions of illegal votes into the system with no evidence. They have filed multiple lawsuits in battleground states alleging that partisan poll watchers didn't have a clear enough view at polling sites in some locations and therefore something illegal must have happened. The claims have been repeatedly dismissed including by Republican judges who have ruled the suits lacked evidence.

But local Republicans in some battleground states have followed Trump in making unsupported claims, prompting grave concerns over potential damage to American democracy.

Trump himself continues to rail against the election in tweets and in interviews though his own administration has said the 2020 election was the most secure ever. He recently allowed his administration to begin the transition over to Biden, but he still refuses to admit he lost.

The issues they've have pointed to are typical in every election: Problems with signatures, secrecy envelopes and postal marks on mail-in ballots, as well as the potential for a small number of ballots miscast or lost.

But they've gone further. Attorney Sidney Powell has spun fictional tales of election systems flipping votes, German servers storing U.S. voting information and election software created in Venezuela "at the direction of Hugo Chavez," -- the late Venezuelan president who died in 2013. Powell has since been removed from the legal team after an interview she gave where she threatened to "blow up" Georgia with a "biblical" court filing.

Barr didn't name Powell specifically but said: "There's been one assertion that would be systemic fraud and that would be the claim that machines were programmed essentially to skew the election results. And the DHS and DOJ have looked into that, and so far, we haven't seen anything to substantiate that."

In the campaign statement, Giuliani claimed there was "ample evidence of illegal voting in at least six states, which they have not examined."

"We have many witnesses swearing under oath they saw crimes being committed in connection with voter fraud. As far as we know, not a single one has been interviewed by the DOJ. The Justice Department also hasn't audited any voting machines or used their subpoena powers to determine the truth," he said.

However, Barr said earlier that people were confusing the use of the federal criminal justice system with allegations that should be made in civil lawsuits. He said a remedy for many complaints would be a top-down audit by state or local officials, not the U.S. Justice Department.

"There's a growing tendency to use the criminal justice system as sort of a default fix-all," he said, but first there must be a basis to believe there is a crime to investigate.

"Most claims of fraud are very particularized to a particular set of circumstances or actors or conduct. ... And those have been run down; they are being run down," Barr said. "Some have been broad and potentially cover a few thousand votes. They have been followed up on."

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Associated Press writers Lisa Mascaro and Eric Tucker contributed to this report.