WASHINGTON — Attorney General William Barr used his final public appearance to undercut President Donald Trump on multiple fronts Monday, saying he saw no reason to appoint a special counsel to look into the president’s claims about the 2020 election or to name one for the tax investigation of President-elect Joe Biden’s son.

In the course of breaking with Trump on matters that have been consuming the president, Barr also reinforced the belief of federal officials that Russia was behind a massive hack of U.S. government agencies, not China as Trump had suggested.

Barr made the comments at a press conference to announce additional criminal charges in the bombing of Pan Am Flight 103, which killed 190 Americans, an issue he had worked on in his previous stint as attorney general in the early 1990s. He chose the announcement, in a case very personal and important to him, for his last public appearance, then took questions.

Barr said the Justice Department’s existing investigation into Hunter Biden’s financial dealings was “being handled responsibly and professionally.”

“I have not seen a reason to appoint a special counsel and I have no plan to do so before I leave,” he said. Nor for election fraud, he said.

Barr had been in lockstep with the president during much of his tenure as Trump’s attorney general. But Trump, as he has done with many others in his inner circle, started criticizing Barr publicly. He was particularly angry that Barr didn’t announce the existence of a two-year-old investigation of Hunter Biden.

And shortly before he announced his resignation, Barr told The Associated Press that he had seen no evidence of widespread voting fraud, despite Trump’s claims to the contrary. Trump has continued to push baseless claims even after the Electoral College made Biden’s victory formal Dec. 14.

A special counsel would make it more difficult for the incoming attorney general and president to close investigations begun under Trump. Doing so could lend a false legitimacy to baseless claims, particularly to the throngs of Trump supporters who believe the election was stolen because he keeps wrongly claiming it was.

Barr’s statements Monday may make it easier for the acting attorney general who takes over, Jeffrey Rosen, to resist pressure from the White House to make such appointments.

In his 2019 confirmation hearing for deputy attorney general, Rosen said he was willing to rebuff political pressure from the White House if necessary. He told legislators that criminal investigations should “proceed on the facts and the law” and prosecutions should be “free of improper political influences.”

“If the appropriate answer is to say no to somebody, then I will say no,” he said at the time.

Trump and his allies have filed roughly 50 lawsuits challenging election results and nearly all have been dismissed or dropped. He’s also lost twice at the U.S. Supreme Court.

With no further tenable legal recourse, Trump has been fuming and peppering allies for options as he refuses to accept his loss.

Among those allies is Rudy Giuliani, who during a meeting Friday pushed Trump to seize voting machines in his hunt for evidence of fraud. The Homeland Security Department made clear, however, that it had no authority to do so. It is also unclear what that would accomplish.

For his part, Barr said he saw no reason to seize them. Earlier this month, Barr also told the AP that the Justice Department and Homeland Security had looked into the claims “that machines were programmed essentially to skew the election results” and ultimately concluded that “so far, we haven’t seen anything to substantiate that.”