WASHINGTON, March 25 (Xinhua) -- Six Democratic committee chairs in the U.S. House of Representatives on Monday requested Attorney General William Barr submit the full report from special counsel Robert Mueller on the Russia investigation to Congress by April 2.

The top House Democrats wrote in a letter to Barr that his summary of the Mueller report "is not sufficient for Congress."

"We look forward to receiving the report in full no later than April 2, and to begin receiving the underlying evidence and documents that same day," the letter said.

The letter was signed by House Judiciary Committee Chairman Jerry Nadler, along with five other House panel chairs.

Their request came a day after Barr submitted to Congress and made public a four-page summary of Mueller's confidential report.

According to Barr's synopsis, Mueller found no evidence of collusion between Donald Trump's campaign and the Russian government during the 2016 U.S. presidential election but did not reach a conclusion as to whether the president had obstructed justice. Barr concluded the special counsel's findings are "not sufficient" to support a charge.

Democrats are demanding the complete release of Mueller's report as well as Barr's appearance before Congress to get a clearer picture of the special counsel's investigation.

Senate Majority Leader Mitch McConnell, a Republican, on Monday blocked an effort to unanimously pass a non-binding measure stating that Congress wants Mueller's report made available to lawmakers and the public.

The measure was passed in an unanimous House vote earlier this month.

Trump said Monday that it is up to Barr to decide whether the report will be released to the public, adding that he isn't thinking about pardoning anyone sentenced during the inquiry.

Mueller took over the Russia investigation in May 2017 after Trump abruptly fired former FBI director James Comey, a move that raised questions about a potential obstruction of justice.

The investigation has led to felony charges against 34 people, including six Trump associates and advisers, and three entities.

Many of the charges against the Trump associates were related to lying to Congress or federal investigators. None of them were directly related to the question of collusion between the Trump campaign and Russia.

Trump has touted Barr's summary as a "complete exoneration."