Top U.S. lawmakers have continued to question the relationship between Russia and President Donald Trump's aides, with a growing number of Republicans joining calls for inquiries into the matter.
The Republican and Democratic leaders of the Senate Judiciary Committee asked U.S. Attorney General Jeff Sessions and Federal Bureau of Investigation (FBI) Director James Comey on February 15 to send the committee documents and provide a briefing on the ouster of Michael Flynn, the White House national security adviser who left after revelations that he discussed U.S. sanctions against Russia with the Russian ambassador before taking office.
Citing reports that both the FBI and Justice Department were involved in events leading to Flynn's departure, Senators Chuck Grassley and Dianne Feinstein said those reports raised "substantial questions" about Flynn's discussions with Russian officials.
Adding to the pressure on the White House were comments by Senate Foreign Relations Committee Chairman Bob Corker, who has been a Trump supporter.
Corker said the Russia issue was threatening Trump's agenda on foreign affairs and domestic matters like health care and tax policy. He questioned whether the White House was able to stabilize itself and said Flynn should testify before Congress.
"Let's get everything out as quickly as possible on this Russia issue," Corker told MSNBC's Morning Joe program. "Maybe there's a problem that obviously goes much deeper than what we now suspect."
Senator Lindsey Graham, who vied with Trump for the Republican presidential nomination last year, called for a broader bipartisan congressional investigation to be conducted by a newly formed special committee rather than existing committees of Congress, if it turns out Trump's presidential campaign communicated with the Russians.
Senate Armed Services Committee Chairman John McCain didn't rule out an independent investigation, but said he and other lawmakers "need to find out a lot of basic information" first about Flynn's communications and the alleged contacts between Russian officials and Trump's campaign.
"Something like this always sucks the oxygen out of the room," McCain said. "The president's national security adviser did not tell the vice president of the United States the truth and had to be fired. It brings up a lot of questions and those questions need to be answered. Right now, without a national security adviser and everything else that's going on in the White House, it is dysfunctional on national security."
Senate Majority Leader Mitch McConnell has said he expects the Senate Intelligence Committee, which is already investigating allegations of Russian meddling in the presidential election, to expand its investigation and interview Flynn.
Senator Roy Blunt, a Republican on the Intelligence Committee, agreed that the committee should expand and expedite its ongoing investigation to address the Flynn ouster.
"I think sooner is better than later," Blunt told reporters. "And I think we can be a long way down the road in 90 days."
Democrats said they doubt the Republican-led Congress or Trump's Justice Department will pursue the matter vigorously enough, and they are demanding an independent investigation into possibly illegal communications between Flynn and the Russian government and any efforts by Flynn or other White House officials to conceal wrongdoing.
The most powerful Democrat in the Senate, Chuck Schumer, said Attorney General Sessions, a close ally of Trump, must recuse himself from any investigation.
"Prosecutors should not be reporting to the first senator who endorsed Donald Trump's campaign," he said.
But the top Republicans in the Senate and House of Representatives have rejected establishing an independent investigative panel like the Watergate prosecutor, saying existing Republican-led committees in Congress can do the job.
Meanwhile, investigations continue within the executive branch after U.S. intelligence agencies concluded last year that Russia hacked and leaked Democratic Party e-mails during the presidential campaign in an effort to tilt the election toward Trump.
The FBI and several U.S. intelligence agencies are now investigating Russian espionage operations in the United States, Reuters reported. They are also looking at contacts between Russian officials and people connected to Trump or his campaign.
The FBI recently questioned Flynn about his telephone contacts with Russian Ambassador Sergei Kislyak in December while the Obama administration was preparing new sanctions against Russia related to its alleged hacking of the election.
Investigators have found no evidence so far of collusion between Russians and Trump's campaign before the election, however, or any evidence of criminal activity by Flynn or anyone else connected to Trump, Reuters reported.
Trump on February 15 railed against "illegal" leaks of classified information about the investigations to the news media and said Flynn had received "unfair treatment" from the media.
Grassley, the Senate judiciary chairman, agreed. He said that while Flynn should be held responsible for any wrongdoing, so should anyone in the government who leaked classified information.
"I think that we need to start considering that it's not only dangerous and scary that some foreign power attempts to influence our elections, but it may be even scarier that intelligence officials in our own government may be trying to undermine our government," he said on a conference call with reporters in Washington.
With reporting by AP and Reuters