WASHINGTON (Reuters) - U.S. President Donald Trump said on Sunday that Special Counsel Robert Mueller should not testify in Congress about the investigation into Russian interference in the 2016 presidential election, after saying on Friday it was up to the Justice Department’s top official.

Trump said on Twitter that Democrats in Congress were seeking a “redo” of Mueller’s report, which declined to conclude whether the president’s efforts to impede the investigation constituted obstruction of justice.

“Bob Mueller should not testify. No redos for the Dems!” Trump tweeted.

Attorney General William Barr, under fire from Democrats for his handling of the report’s release, has said he has no problem with Mueller testifying. On Friday, Trump told reporters it was up to Barr to decide if Mueller should testify.

The Mueller report chronicled Russian efforts to help Trump win election in 2016 but found that Trump and his campaign did not engage in a criminal conspiracy with Moscow.

The Republican president has derided the investigation as a costly “witch hunt” and sought to characterize the report’s findings as a victory.

The Democratic-led House of Representatives Judiciary Committee appears closest to arranging for Mueller to testify, possibly as soon as May 15.

Peter Carr, a spokesman for Mueller, declined to comment on Sunday.

Barr is headed for another showdown with Congress on Monday if he fails to meet a morning deadline to hand over the full, unredacted Mueller report requested by Democrats.

Democratic Representative Adam Schiff, who chairs the House Intelligence Committee, said Democrats needed to hear from officials beyond Barr, including former White House counsel Don McGahn. Mueller and McGahn “will testify. The American people deserve the truth,” he said on Twitter.

Trump said on Friday he would decide within a week or so whether to assert executive privilege to block McGahn from testifying before Congress.

Last month, the House Judiciary Committee subpoenaed McGahn seeking documents by Tuesday and for him to testify on May 21.