WASHINGTON, DC - U.S. Attorney General William Barr on Monday quashed calls by U.S. President Donald Trump for the Justice Department to investigate his predecessor, Barack Obama, saying he doesn't expect the department to probe either Obama or his vice president, Joe Biden, in connection with the controversial Russia investigation.

"As to President Obama and Vice President Biden, whatever their level of involvement, based on the information I have today, I don't expect Mr. Durham's work will lead to a criminal investigation of either man," Barr said at a press conference, referring to a Justice Department review of the Russia investigation led by U.S. Attorney John Durham.

Barr claimed the Justice Department's investigation of Russian meddling in the 2016 U.S. presidential election to help Trump defeat Democrat Hillary Clinton involved abuses by law enforcement and intelligence agencies under the Obama administration. But citing a recent Supreme Court ruling involving the so-called Bridgegate scandal, he said not every abuse of power is a federal crime.

That scandal involved efforts by associates of former New Jersey Governor Chris Christie to retaliate against a political opponent by manufacturing massive traffic jams over the George Washington Bridge. On May 7, the Supreme Court unanimously ruled that while the two officials had committed "deception, corruption and abuse of power," federal laws do not "criminalize all such conduct."

Barr's comments came in response to a question about Trump's calls for the Justice Department and Congress to investigate Obama for seeking a probe of Trump national security adviser Michael Flynn's conversations with the Russian ambassador to Washington shortly before Trump took office in January 2017.

That investigation led to Flynn's guilty plea for lying to the FBI - a plea Barr now is seeking to overturn. In a recent tweet, Trump alleged, without specifying, that Obama had committed "the biggest political crime in American history" as part of the Russia investigation.

Asked about Barr's comments, Trump told reporters Monday at the White House, "I'm a little surprised by that statement. I think he said 'as of this moment.' I guess. But if it was me, I guarantee they'd be going after me."

Barr last year ordered an internal Justice Department review of the Russia probe and tapped Durham to lead the effort. The Durham investigation is ongoing, and Barr left open the possibility that other Obama administration officials would be criminally charged.

"Our concern over potential criminality is focused on others," Barr said in response to a question about Trump's call for an investigation.

Although Barr did not identify the targets of the investigation, Durham is believed to be examining the role of former CIA Director John Brennan and former Director of National Intelligence James Clapper, among other Obama administration officials.

The Justice Department's investigation of suspected ties between the Trump campaign and Russia ended last year, concluding that despite numerous contacts between the Trump campaign and Russian operatives there was not enough evidence of a criminal conspiracy.

Barr was a critic of special counsel Robert Mueller's probe before he was tapped by Trump as his attorney general after Trump fired Jeff Sessions. Echoing Trump's criticism of the Russia probe, Barr lashed out at "the law enforcement and intelligence apparatus" for promoting a "false and utterly baseless narrative" about Trump's collusion with Russia.

"What happened to the president in the 2016 election, and throughout the first two years of his administration, was abhorrent," Barr said. "It was a grave injustice and it was unprecedented in American history."

Portraying himself as an impartial chief law enforcement officer, Barr said he would not allow the Justice Department to conduct politically motivated investigations of presidential candidates. "Any effort to pursue an investigation of either candidate has to be approved by me," he said.

Barr, who first served as attorney general in the administration of the late President George H. W. Bush, long enjoyed a reputation as a highly respected lawyer.

But since returning to the helm of the Justice Department last year, his advocacy of the president's policies and intervention in high-profile cases involving Trump associates have earned him criticism as the "president's personal lawyer."

Last week, a group of more than 1,900 former Justice Department and FBI officials signed a letter demanding Barr's resignation after he directed the Justice Department to drop its criminal case against Flynn. A federal judge is reviewing the recommendation.

In February, Barr faced a similar backlash after he intervened in long-time Trump associate Roger Stone's case, directing prosecutors to lower their sentencing recommendation. At the time, more than 1,100 former Justice Department officials and federal prosecutors demanded Barr's resignation.