U.S. Sen. John McCain (R-AZ) (L) and U.S. Sen. Charles Schumer (D-NY) share a moment as they speak to members of the press outside the Senate Chamber June 27, 2013 at the U.S. Capitol in Washington, DC. Alex Wong/Getty Images US Republican and Democratic senators on Sunday called for a special bipartisan panel to investigate cyber attacks against the United States by foreign countries with a focus on Russia's alleged efforts to influence the US presidential election.

Charles Schumer, who will be the Senate Democratic leader in the new US Congress in January, and John McCain, the chairman of the Senate Armed Services Committee, said separately on Sunday that a select committee was needed to ensure effective congressional focus on the hacking of Democratic Party emails during the campaign.

"The fact that they're hacking our political system and trying to influence the outcome, as it seems to be, that is serious, serious stuff," Schumer of New York told a news conference in New York. He said the panel should also examine hacking by other countries including China and Iran.

Two other senators, Republican Lindsey Graham of South Carolina and Democrat Jack Reed of Rhode Island, joined Schumer and McCain of Arizona in sending a letter to Senate Republican leader Mitch McConnell requesting the panel, Schumer said.

US intelligence agencies have concluded that Russia tried to influence the election by hacking individuals and institutions, including Democratic Party bodies.

The matter has angered President-elect Donald Trump, who says he won the Nov. 8 vote fairly.

Russian officials have denied accusations of interfering in the Nov. 8 US election.

On Friday, US President Barack Obama suggested that Russian President Vladimir Putin personally authorized the Democratic Party email hacks.

Vladimir Putin. Sean Gallup/Getty Images

McCain told CNN's "State of the Union" program that the US response to the Russian attacks has been "totally paralyzed" and said cyber warfare "is perhaps the only area where our adversaries have an advantage over us."

The Trump transition team did not respond to a request for comment.

John Podesta, Hillary Clinton's presidential campaign chairman, also said on Sunday that it was an "open question" whether Trump's advisers colluded with Russia to hack into Democratic Party emails to try to sway election outcome.

Leaked emails had revealed details of paid speeches that Clinton gave to Wall Street, party infighting and comments from Clinton top aides who said they were shocked about the extent of her use of a private server to send emails while US secretary of state.

The leaks led to embarrassing media coverage and prompted some party officials to resign.

Podesta said there was evidence that Trump associates had contact with a Russian intelligence official and the website Wikileaks before US intelligence agencies accused Russia of being behind computer attacks of Democratic emails, including Podesta's. But he did not specify what the evidence was.

"It's very much unknown whether there was collusion. I think Russian diplomats have said post-election that they were talking to the Trump campaign," he told NBC's "Meet the Press" program.

"Not what Mr. Trump knew, but what did 'Trump Inc' know and when did they know it? Were they in touch with the Russians? I think those are still open questions," he added.

Asked if it was a free and fair election, Podesta replied: "I think it was distorted by the Russian intervention, let's put it that way."

Clinton campaign manager John Podesta speaks to members of the media outside Democratic presidential candidate Hillary Clinton's home in Washington, Wednesday, Oct. 5, 2016. AP/Andrew Harnik

In a separate interview, Trump's incoming White House chief of staff, Reince Priebus, rejected the notion that Trump or his associates were aware of and in touch with the Russians during the hack attack.

"Even this question is insane," Priebus told Fox News Sunday. "Of course we don’t interface with the Russians."

The controversy, which includes a formal US Justice Department probe, has intensified interest in a crucial Monday vote by the Electoral College, which determines the outcome of US presidential elections.

Trump won the Electoral College but lost the popular vote.

Electoral College members will meet in every state to cast the ballots that will officially declare winners of the presidential and vice presidential contests.

The voting is usually a formality. Podesta has called for the electors to be briefed about the hacking before they vote.