Top Republicans Paul Ryan and Mitch McConnell have said they will support further investigation of findings that Russian hackers meddled in the November election.
The House speaker and Senate majority leader said any foreign intervention in the polls was unacceptable.
Donald Trump has repeatedly poured scorn on the claims, made by the CIA.
The CIA concluded on December 9 that Russia’s motive was to help Donald Trump.
Mitch McConnell and Paul Ryan said their respective intelligence committees would investigate the allegations.
“Any foreign breach of our cyber-security measures is disturbing and I strongly condemn any such efforts,” Senator Mitch McConnell told reporters, adding that “the Russians are not our friends”.
Paul Ryan echoed these remarks, but warned against exploiting the work of the intelligence community for “partisan purposes”.
The remarks came amid suggestions by Donald Trump that the claims were politically motivated.
On December 11, the president-elect told Fox News the Democrats were disseminating the “ridiculous” hacking reports because they lost the election.
Then on the next day Donald Trump tweeted: “Can you imagine if the election results were the opposite and WE tried to play the Russia/CIA card. It would be called conspiracy theory!
“Unless you catch <<hackers>> in the act, it is very hard to determine who was doing the hacking. Why wasn’t this brought up before election?”
The FBI said two month ago that it believed Russia was behind the Democratic Party hacks, but on December 9 the CIA went further by concluding Russia’s motive was to help Donald Trump.
On December 12, the Hillary Clinton campaign, which lost to Donald Trump in last month’s election, said it was supporting an effort by a handful of members of the electoral college to request an intelligence briefing on the latest hacking allegations.
The Electoral College meets next week to ratify the results of the election.
Last week, President Barack Obama has ordered a complete review of the hacks, which targeted emails at the Democratic Party and John Podesta’s emails.
The contents of the emails, passed to WikiLeaks and posted online, were embarrassing to the Democrats and shook up the presidential campaign.