Intelligence officials warned lawmakers in a briefing before the House Intelligence Committee last week that the Russians are continuing their efforts to attack the democratic process and interfere in the 2020 election, and that one prong is aimed at helping re-elect President Trump.

"The message was, it appears they're favoring one candidate over another, and everybody should be cautious," a source who attended the Hill meeting confirmed to CBS News. The New York Times first reported on the briefing at the Capitol. Officials at the briefing offered an assessment reflective of the conclusions of multiple agencies, and lawmakers on both sides asked to see the underlying intelligence.

But there was reportedly bipartisan pushback on the House briefing concerning its depth, credibility and the scope of the evidence, a senior administration official told CBS News. The DNI official overseeing election security threats, Shelby Pierson, was not able to present a rock-solid case proving Russia's assistance, according to the senior administration official. A House Intelligence Committee official denied there had been bipartisan pushback on the briefing.

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A day later, on Friday, February 14, intelligence officials briefed the White House on election security and also offered the same assessment — that Russia is trying to help Mr. Trump win his re-election bid in 2020 — the senior administration official said.

On Friday, Moscow denied that it's trying to interfere in the election and help Mr. Trump, and said the reports are the result of paranoia, according to the Reuters news service.

Mr. Trump was also dismissive, tweeting Friday, "Another misinformation campaign is being launched by Democrats in Congress saying that Russia prefers me to any of the Do Nothing Democrat candidates who still have been unable to, after two weeks, count their votes in Iowa."

Sources tell CBS News that Mr. Trump was unaware of the classified House briefing and furious when he found out about it from House Republicans. According to the senior administration official, Mr. Trump "blew his stack" and repeatedly used an expletive.

The Washington Post first reported that Mr. Trump had quarreled with his acting director of national intelligence, Joseph Maguire, after intelligence officials briefed lawmakers on the threat of Russian interference. Mr. Trump announced Wednesday that Richard Grenell, the current ambassador to Germany, would replace Maguire in the position.

But a congressional source told CBS News "there is absolutely no connection to replacing Maguire and the briefing — Maguire was on the way out anyway."

The source at the Hill meeting also confirmed that some of the president's Republican allies on the House Intelligence Committee, who were also in the meeting, "questioned the validity of the information." But the the information presented wasn't particularly surprising, the source said, since former Director of National Intelligence Dan Coats had already warned months ago that when it comes to Russian election interference, "the lights are still flashing red."

House Speaker Nancy Pelosi tweeted late Thursday that another briefing is planned, saying, "We await the election security briefing for Members on March 10."

She also chided the president:

American voters should decide American elections — not Vladimir Putin. All Members of Congress should condemn the President’s reported efforts to dismiss threats to the integrity of our democracy & to politicize our intel community. https://t.co/uiAU2lXwrs — Nancy Pelosi (@SpeakerPelosi) February 21, 2020

Intelligence officials have been suggesting publicly and privately that Russia and other adversaries have been refining their disinformation methods, working to spread and amplify their messages through "authentic" U.S. sources, rather than creating personas that can be flagged by social media companies as fake identities.

Top administration officials, including Attorney General Bill Barr, FBI Director Christopher Wray and ex-Acting DNI Joseph Maguire, alluded to this phenomenon in a USA Today op-ed Wednesday.

They warned Americans that some foreign governments have tried to meddle in U.S. affairs "by attempting to shape public opinion and voter perceptions."

"Often, we see foreign adversaries amplifying messages some Americans create and share with each other, in an effort to stoke hostility among us and make us appear more divided than we are," they wrote.

Multiple intelligence and government officials have said they fear that U.S. adversaries could also use ransomware to target state and local governments. And they worry that there could be cyber operations launched that target voting infrastructure, to obtain voter data not to change it, but rather to microtarget voters with disinformation.

Nancy Cordes, Catherine Herridge, Major Garrett, Paula Reid, Olivia Gazis and Grace Segers contributed to this report.