President-elect Donald Trump was hours away on Friday from listening to the nation's top intelligence officials make their most detailed and persuasive case yet that Russia's government interfered in this year's US presidential elections.

Without seeing the intelligence, Trump dismissed the findings and told The New York Times the focus on Russia's involvement is a “political witch hunt” by adversaries who are embarrassed they lost the election.

“They got beaten very badly in the election,” Trump told the Times. “They are very embarrassed about it. To some extent, it's a witch hunt. They just focus on this.”

The officials Director of National Intelligence James Clapper, CIA Director John Brennan and FBI Director James Comey are preparing to point to multiple motives for Moscow's alleged meddling as they brief Trump on their classified report on Friday in New York.

They briefed senior lawmakers Friday morning. President Barack Obama received a briefing on Thursday.

A declassified version of the report is expected to be released on Friday afternoon, according to one US official, who wasn't authorized to comment publicly and requested anonymity.

On Capitol Hill, the intelligence officials and lawmakers refused to comment when they left the briefing for lawmakers. Asked how the briefing went, National Security Agency Director Adm. Mike Rogers responded, “Have a nice day.”

House Minority Leader Nancy Pelosi, D-Calif., said the intelligence report was “quite a stunning disclosure” and said parts will be released today, though she didn't provide any specifics. She made the comments at her weekly Capitol Hill news conference.

Several advisers were to joint Trump and Vice President-elect Mike Pence for Friday's intelligence briefing. Among them are incoming White House chief of staff Reince Priebus; incoming national security adviser Michael Flynn ; incoming deputy national security adviser K.T. McFarland; Thomas Bossert, Trump's pick for homeland security adviser; and Rep. Mike Pompeo, R-Kan., his choice to head the CIA.

Upset that NBC released information about the hacking, Trump tweeted: “I am asking the chairs of the House and Senate committees to investigate top secret intelligence shared with NBC prior to me seeing it.”

NBC reported that intelligence officials have identified proxies that Russia used to pass hacked Democratic emails to WikiLeaks, which then released them to the public.

Since winning the election, Trump has repeatedly questioned intelligence officials' assessments that Russia was behind the hacking of the Democratic National Committee and individual Democrats like Hillary Clinton campaign chairman John Podesta.

Trump remained dubious about the assertion even on the eve of his intelligence briefing, asking how officials could be “so sure” about the hacking if they had not examined DNC servers.

“What is going on?” he wrote on Twitter.

A senior law enforcement official said the FBI repeatedly stressed to DNC officials the importance of obtaining direct access to the servers “only to be rebuffed until well after the initial compromise had been mitigated.”

The official said the FBI had to rely on a “third party” for information, but did get access to the material it needed.

The Washington Post, citing anonymous US officials, reported on Thursday that intelligence agencies have identified parties who delivered stolen Democratic emails to WikiLeaks.

The officials also said there were disparities between efforts to infiltrate Democratic and Republican networks, and said the US intercepted communications in which Russian officials celebrated Trump's victory. It was not clear which of those details were included in the classified report.

Sean Spicer, whom Trump has chosen as White House communications director and press secretary, said the billionaire business will go into Friday's meeting “prepared to listen and understand how they got to the conclusions.”

Asked on ABC's “Good Morning America” if Trump would have an open mind, Spicer replied, “100 percent.”

“The president-elect, I think, has a healthy skepticism on everything,” the spokesman said, adding that “a rush to judgement is not in the country's best interest.”

“I think the idea that he's approaching this in a very logical, very methodical way ... is the right way to go about it,” Spicer added.