'To date, we have not seen fraud on a scale that could have effected a different outcome in the election,' he told the Associated Press.
The US attorney general rejected Republican claims of significant voter fraud in the presidential election on Tuesday, adding to the pressure on President Donald Trump to give up his quixotic effort to overturn Joe Biden's clear victory.
Bill Barr's comments confirmed the conclusions of the Department of Homeland Security, US intelligence and independent poll watchers that the 2020 election was, in the language of government officials, the "most secure in American history."
"To date, we have not seen fraud on a scale that could have effected a different outcome in the election," he told the Associated Press.
Barr's interview came as Trump persisted in claiming, without evidence, that fraudulent voting practices and systems in key states such as Michigan, Pennsylvania and Georgia had robbed him of a second term.
In tweets Tuesday afternoon, Trump highlighted testimony being offered in a public hearing on the election in Michigan, which has already certified Biden's win in the state, and a separate Republican-organized event in Virginia.
"People are coming forward like never before. Large truck carrying hundreds of thousands of fraudulent (FAKE) ballots to a voting center? TERRIBLE - SAVE AMERICA!" he wrote.
In several legal filings -- all rejected by the courts -- the Trump campaign has sought to invalidate millions of votes for Biden based on claims that lacked any evidence.
According to official vote tallies, Biden earned 6.2 million more votes than Trump and captured 306 state-by-state Electoral College votes, well above the 270 needed to win the presidency.
But Trump's campaign has strived to delay the popular vote tally from being finalized before the Electoral College meets on December 14 to certify the election winner.
His attorneys, led by Rudy Giuliani, have made numerous allegations ranging from ballot-box stuffing and fake ballot printing, to thousands of dead people having voted, to vote-counting machines being programed to favor Biden.
'Someone is going to get killed'
The campaign to challenge the results has led to rising unease within the Republican party including an emotional rebuke directed at Trump from the man in charge of Georgia's voting systems.
Gabriel Sterling called a press conference to tell the president he had failed to speak out against violent threats to election officials.
"Stop inspiring people to commit potential acts of violence," he said. "Someone is going to get hurt, someone is going to get shot, someone is going to get killed. And it's not right."
Separately on Tuesday, staunch Trump supporter and Senate Majority Leader Mitch McConnell gave his clearest acknowledgment yet that Biden would move into the White House next month.
Discussing stalled negotiations over a stimulus package to jump-start the virus-battered US economy, McConnell said: "There's likely to be a discussion about some additional package of some size depending on what the new administration wants to pursue."
Barr, an ally of Trump, didn't address specific claims, but dismissed the idea of any "systemic" fraud that would have changed the outcome of the vote.
Any problem for which there has been evidence, Barr noted, would impact an insignificant number of votes.
"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," he told the AP.
"So far, we haven't seen anything to substantiate that," he added.
Giuliani rejects Barr
There was no immediate reaction to Barr from Trump. But in a joint statement, Giuliani and Jenna Ellis, a senior legal advisor to the outgoing president's campaign, dismissed the remarks.
"With all due respect to the attorney general, there hasn't been any semblance of a Department of Justice investigation," they said.
"We have gathered ample evidence of illegal voting in at least six states, which they have not examined.”
Recent news reports have said that Trump is unhappy with Barr for not making efforts to support the president's reelection.
But, likely pleasing Trump, on Tuesday he revealed that he had named an independent special prosecutor to investigate the Justice Department and FBI investigators who probed links between Trump's campaign and Russia in the 2016 election.
Trump has claimed that those investigators, including former special counsel Robert Mueller, were part of a corrupt, political "witch hunt" by the "deep state" to undermine his administration.