President-elect Donald Trump is expected to be briefed Friday on a report prepared by the U.S. intelligence community on Russian hacking activities in the presidential election -- after he spent this week still questioning the veracity of their previous assessments.

On Thursday, President Obama received a briefing on the report -- prepared by the CIA, FBI and NSA -- which he had ordered in December. Director of National Intelligence James Clapper said Thursday that an unclassified version of the report will be made public early next week. In testimony before the Senate Armed Services Committee Thursday, Clapper previewed some of the report’s findings.

“Hacking was only part of it,” he said about Russia’s cyber activities during the election. “It also entailed classical propaganda, disinformation, fake news.”

Clapper will be one of four intelligence chiefs to brief Mr. Trump on the report Friday at Trump Tower in New York. The other briefers will be CIA Director John Brennan, FBI Director James Comey and National Security Agency Director Adm. Mike Rogers.

For weeks, the president-elect has been questioning the U.S. intelligence community’s integrity and its assessment that Russia not only launched cyberattacks against the U.S. to sow doubt in the election, but to sway the outcome in favor of Mr. Trump. Since the final weeks of the campaign, he also doubted that Russia was responsible.

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Mr. Trump claimed on New Year’s Eve that he had information no one else had on Russian hacking and that he would reveal it publicly this week, but he has not yet followed through on that statement. On Wednesday, he posted a tweet indicating he’s still not convinced Russia is to blame for cyberattacks against the Democratic National Committee (DNC), other political groups and Hillary Clinton’s campaign chairman John Podesta.

The "Intelligence" briefing on so-called "Russian hacking" was delayed until Friday, perhaps more time needed to build a case. Very strange! — Donald J. Trump (@realDonaldTrump) January 4, 2017

A number of Republicans in Congress like Rep. Michael McCaul, R-Texas, chairman of the Homeland Security Committee, are adamant about the need for the new administration to develop a more clear-cut cyber policy and to punish Russia for its actions. McCaul expressed confidence in the intelligence Thursday, saying that the evidence he was briefed on in both classified and unclassified settings “was very clear,” and he said that it was clear the attacks were “nation state-based.”

“I think the incoming administration needs to take a strong stance against what has happened,” he told reporters.

Sen. John McCain, R-Arizona, and other Republicans warned at his committee’s hearing that Russia must suffer the consequences.

“Every American should be alarmed by Russia’s attacks on our nation,” said McCain. Later in the day, he told reporters that the Trump administration should work with Congress to craft a cyber policy.

“We’ll be glad to work with them, but they’ve got to have a policy and a strategy,” he said as he continued to blast the Obama administration for lacking a plan. “They’ve never had one. They’ve reacted to every single attack in a different way. It’s just crazy.”

Clapper, Rogers and undersecretary of defense for intelligence, Marcel Lettre, issued a joint statement Thursday, warning that Russia is a “full-scope cyber actor.”

“We assess that only Russia’s senior-most officials could have authorized the recent election-focused data thefts and disclosures, based of the scope and sensitivity of the targets. Russia also has used cyber tactics and techniques to seek to influence public opinion across Europe and Eurasia,” they said. “Looking forward, Russian cyber operations will likely target the United States to gather intelligence, support Russian decision-making, conduct influence operations to support Russian military and political objectives, and prepare the cyber environment for future contingencies.”

Last week, the Obama administration announced a new series of sanctions against Russian intelligence agents and entities that the U.S. says were responsible for hacks into the DNC and other servers. In addition to the targeted sanctions, 35 Russian operatives were expelled from the U.S. in retaliation.

Sen. Lindsey Graham, R-South Carolina, said those actions weren’t good enough and had some advice for the president-elect: “When you listen to these people [in the intelligence community,] you can be skeptical, but you have to understand they’re the best among us.”

“I think what Obama did was throw a pill. I’m ready to throw a rock,” Graham said. “If we don’t throw rocks, we’re going to make a huge mistake.”

Over the next week, Sen. Ben Cardin, D-Maryland, the top Democrat on the Senate Foreign Relations Committee, plans to roll out legislation containing tougher sanctions against Russia.

“That hearing today gave a great boost to sanctions,” McCain said. Clapper’s testimony and Roger’s testimony this morning helps that process along and resolved any doubts as to what the intelligence part of our government thinks.”

Mr. Trump, meanwhile, appeared to side this week with WikiLeaks’s Julian Assange who again denied that their source for hacked emails was not the Russian government.

Julian Assange said "a 14 year old could have hacked Podesta" - why was DNC so careless? Also said Russians did not give him the info! — Donald J. Trump (@realDonaldTrump) January 4, 2017

Several lawmakers slammed Mr. Trump for questioning the integrity of the intelligence community. Sen. Claire McCaskill, D-Missouri, asked Clapper, “Who benefits from a president-elect trashing the intelligence community?”

“I think there is an important distinction here between healthy skepticism,” Clapper said, “...I think there’s a difference between skepticism and disparagement.”

Speaker Paul Ryan, R-Wisconsin, had positive, but qualified words for the intelligence community.

“I do have faith that our men and women in the intelligence community are doing an incredible job, sacrificing for our country,” he told reporters Thursday, “but there’s always room for improvement.”

On the question of whether Russians meddled in the presidential election, though, Ryan firmly believes the intelligence. “Did the Russians hack us? Yes. Is it right for any country to meddle in our elections? No,” he said on “The Jerry Bader Show.”

CBS News’ Alan He and Catherine Reynolds contributed to this report.