WASHINGTON (Reuters) - Republicans in Congress on Wednesday brushed aside calls to investigate possible political interference at the U.S. Justice Department after the agency asked for a lighter prison term for President Donald Trump’s longtime adviser Roger Stone.

The Justice Department’s decision to back off its sentencing recommendation of seven to nine years for the Republican operative sent shock waves through Washington and prompted all four prosecutors to quit the case and one to quit the agency.

“There should be an investigation,” said House of Representatives Speaker Nancy Pelosi, the top Democrat in Congress. Other Democrats accused Trump of purging the U.S. government of perceived enemies following his acquittal on impeachment charges last week.

They said they would question Attorney General William Barr about the matter when he testifies before Congress on March 31.

“You have taken steps that raise grave questions about your leadership of the Department of Justice,” Democratic members of the House Judiciary Committee wrote to Barr in a letter.

Republican lawmakers, who nearly all voted to acquit Trump of impeachment charges, offered muted criticism of the president but shrugged off suggestions they should investigate whether his political concerns were influencing law enforcement.

“I doubt that would do much,” said Mitt Romney, the only Republican senator to vote to remove Trump from office in the impeachment trial.

After the Justice Department decision, Trump on Wednesday praised Barr, his appointee to the law enforcement job, for “taking charge of a case that was totally out of control and perhaps should not have even been brought.”

Speaking to reporters later at the White House, Trump thanked Justice Department officials for retracting the prison term recommendation. He declined to say whether he would pardon Stone. “They treated Roger Stone very badly,” he said.

Lindsey Graham, the Republican chairman of the Senate Judiciary Committee, said he would not call Barr to testify about the revised sentencing decision.

Stone, a self-proclaimed “dirty trickster,” was found guilty last year of lying to Congress, obstruction and witness tampering.

After Trump criticized prosecutors who recommended the seven-to-nine-year prison term, the Justice Department asked Judge Amy Berman Jackson to ignore that filing and impose whatever sentence she thought appropriate.

Justice Department officials and the White House said Trump did not influence that decision.

“While he has the right to have a conversation with the attorney general, he did not,” White House spokesman Hogan Gidley told reporters.

TRUMP TARGETS JUDGE, PROSECUTORS

Trump targeted the judge and the outgoing prosecutors in other tweets, and retweeted a post that urged a full pardon for Stone as well as Michael Flynn, another former Trump adviser.

Stone is due to be sentenced on Feb. 20 after being found guilty in November on seven counts of lying to Congress, obstruction and witness tampering stemming from a government investigation into Russian meddling in the 2016 U.S. presidential election.

Stone and his lawyers have not spoken with Trump about the latest developments in his case, according to two sources familiar with the matter.

The White House also on Tuesday dropped a top prosecutor who oversaw the Stone case, withdrawing the nomination for Jessie Liu to serve in the Treasury Department. Liu had been scheduled to appear publicly before the Senate on Thursday.

The White House declined to comment on Liu’s nomination or to say whether Trump would pardon Stone or Flynn.

Senate Democratic Leader Chuck Schumer asked the Justice Department’s internal watchdog to investigate, and Senator Elizabeth Warren, a Democratic presidential candidate, said Barr should resign or face impeachment.

“Trump is going around getting even with people. Senate Republicans told us he was going to get better, and he didn’t,” Democratic Senator Sherrod Brown told reporters.

Several Republicans said Trump should not have shared his opinion about the Stone case.

“The president should not have gotten involved,” said Republican Senator Susan Collins, who said last week that she thought Trump would moderate his behavior after impeachment.

Others said they saw nothing wrong.

“I’m not disturbed about it at all,” Republican Senator Tim Scott told reporters.