Two U.S. intelligence officials have confirmed to NBC News that FBI Director James Comey and Director of National Intelligence James Clapper agree with a CIA assessment that Russia intervened in the 2016 election in part to help Donald Trump win the presidency.

The officials said electing Trump was only part of what Russia was trying to accomplish. The larger goal, they said, was to undermine confidence in American democracy.

"Mostly they wanted to build uncertainty and challenge faith in the American election system," said one official. The FBI's view has been that Russia's main goal was causing mischief, said the official. That Russia also supported Trump was "one part" of the FBI assessment.

In a memo first reported by the Washington Post and confirmed by NBC News, CIA Director John Brennan told agency staff that he had met separately with Clapper, who oversees 17 U.S. intelligence agencies, and with Comey. "There is strong consensus among us," wrote Brennan, "on the scope, nature and intent of Russian interference in our presidential election."

"In recent days, I have had several conversations with members of Congress, providing an update on the status of the review as well as the considerations that need to be taken into account as we proceed."

Related: Why Obama Didn't Do More About Russian Hack

Intelligence officials had earlier briefed Congress on a CIA assessment that the Russian hacking was intended not just to undermine the election and harm Hillary Clinton, but ultimately to help Donald Trump win. The other 16 agencies and the FBI did not publicly endorse the CIA's assessment.

The confirmation that major intelligence agencies agree on the nature and intent of the Russian operation may put additional pressure on Donald Trump and his supporters, who have sought to portray the government as divided about what happened.

Republicans in Congress who oversee intelligence agencies appeared to be split Friday over the latest intelligence assessments.

Richard Burr of North Carolina, who chairs the Senate Intelligence Committee, issued a statement Friday endorsing the intelligence and the men and women who collect it. Burr promised a committee investigation of "the cyber activity directed against our nation by the Russian Government." He added that intelligence officers "check politics at the office door and focus on their mission," in what appeared to be a message to Trump, who has suggested that U.S. spies are not to be trusted.

But Rep. Devin Nunes of California, a Trump transition official who chairs the House Intelligence Committee, issued his second statement in three days complaining that his committee had not been briefed on the conclusion by the CIA that Russia intended in part to elect Donald Trump.

"We have not received any information from Intelligence Community (IC) agencies indicating that they have developed new assessments on this issue," Nunes said.

A U.S. official said Nunes had been briefed as part of the "Gang of 8," the Congressional leaders who receive the most sensitive intelligence. A Congressional aide insisted that was not the case.