Erin Kelly, Deirdre Shesgreen

USA TODAY

Democrats in Congress raced to every open microphone Wednesday to demand a broad and independent investigation of Russian ties to Donald Trump's presidential campaign and the president's handling of information about his subordinates' contacts with Russia.

Democratic leaders said National Security Adviser Michael Flynn's resignation over his pre-inauguration telephone calls with the Russian ambassador and news reports indicating additional contacts between Trump's camp and Russian intelligence agents have raised a spate of new questions requiring an independent probe.

"Every White House press briefing and early morning tweet seemingly introduces new inconsistencies and contradictions that demand a full accounting," Senate Minority Leader Chuck Schumer, D-N.Y., said on the Senate floor Wednesday. "Every report that suggests deeper ties between the Trump campaign and the Russian government needs to be followed up on and verified."

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Senate Democrats convened an "emergency" meeting of their caucus on Wednesday to discuss their strategy for advancing investigations.

Immediately following that meeting, Schumer said Democrats had agreed on three principles to guide investigations:

Attorney General Jeff Sessions must recuse himself from any investigations by the FBI and federal prosecutors because of his previous role as a national security adviser to the Trump campaign.

All emails and other records relevant to the investigations must be preserved from the Trump campaign, the transition team and the administration.

Campaign and transition officials, including Flynn and former Trump campaign manager Paul Manafort, must be available to testify — publicly and under oath — before congressional committees conducting investigations. Manafort resigned from the Trump campaign last August amid controversy over his lobbying work for pro-Russian Ukrainian oligarchs.

"I've been in Congress for a long time; I've never seen anything like this," Schumer told reporters. "These reports and revelations should not pit the two parties against one another. They should unite the parties in pursuit of the full truth. We are Americans before we are Democrats or Republicans. Nothing less than our system of checks and balances, democratic institutions, the rule of law and our national security is at stake."

A group of 11 Democratic senators, led by Sen. Richard Blumenthal of Connecticut, called for the appointment of an independent special counsel to investigate Flynn's contacts with Russia.

"An independent investigation is now necessary to determine what General Flynn did, who knew about it, and when," the senators wrote in a Wednesday letter to Sessions. "To maintain the confidence, credibility and impartiality of the Department of Justice, we urge you to immediately appoint an independent Special Counsel to investigate collusion with the Russian government by General Flynn and other Trump campaign, transition, and Administrative officials."

In a rare bipartisan approach to the issue, Senate Judiciary Chairman Chuck Grassley, R-Iowa, and Sen. Dianne Feinstein of California, the senior Democrat on the panel, wrote a joint letter to Sessions and to FBI Director James Comey on Wednesday requesting a Justice Department briefing and documents about the events that led to Flynn's resignation.

Specifically, the two senators are seeking details of Flynn’s reported communications with Russian officials, the Justice Department’s response, and potential leaks of classified material. They asked for a briefing for committee members during the week of Feb. 27.

"We request that individuals with specific knowledge of these issues from both the FBI and Justice Department brief committee members and staff," the senators wrote. "We similarly request copies of the transcripts of Mr. Flynn's intercepted calls and the FBI report summarizing the intercepted calls referenced in the media. We anticipate that some of these documents may be classified, some may not, and others may contain both classified and unclassified information."

Feinstein said she is satisfied — for now — that the investigation can be handled by the Judiciary and Intelligence committees.

“I think we just need to move forward very aggressively," she said.

Sen. Joe Manchin, D-W.Va., a member of the Intelligence Committee, said he supports any and all investigations into the matter. The Intelligence Committee is "thick and heavy" into its own investigation, he said, and he hopes the panel will call Flynn, Manafort and others to testify in public sessions if possible.

"Let’s bring them all in,” Manchin said. “We’re very much concerned about being as public as we can up to the secure level."

Manchin said the panel's chairman, Sen. Richard Burr, R-N.C., is on board with conducting the probe "in the most open light that we can."

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Most Republicans on Tuesday said they supported investigating Flynn's contacts with Russia, but they suggested it could be handled by the House and Senate intelligence committees, which are already probing Russian attempts to interfere in the election last year.

But Sen. Lindsey Graham, R-S.C., told ABC News on Wednesday, “If there are contacts between Trump officials and Russian intelligence operatives during the campaign, we need a joint select committee in Congress to get to the bottom of it and also look at Trump's business ties to Russia — if it is true.”

Graham said there should be a preliminary investigation first to make sure there is credibility to the allegations of repeated contacts between the Trump campaign and Russian intelligence operatives. If they are credible, Graham said, a joint select committee would be the best way to investigate.

Sen. Bob Corker, R-Tenn., who is chairman of the Senate Foreign Relations Committee, said Congress needed to find “a non-hysterical but sobering way” to get to the bottom of the allegations.

He said the constant “dribble” of damaging news about Trump and Russia was interfering with Congress’ ability to focus on urgent policy matters.

“It’s obviously disruptive to governing,” Corker said. “We need to figure out way to better handle this and I don’t know what the answer is.”

He said the Senate Intelligence Committee probe might be the best way for that to happen and expressed concern that an independent probe would simply drag the process out.

“The last independent probe was a 2 ½ year process,” Corker said, referring to the commission created to probe the Sept. 11 terrorist attacks. “I’m not sure that’s what the American people would sign up for."

Intelligence agencies announced last year that Russia was behind the hacking of Democratic Party email accounts in an attempt to undermine the presidential election.

Top House Democrats sent a letter Wednesday to White House Counsel Donald McGahn asking a series of questions about his office's review of Flynn's contacts with Russian ambassador Sergey Kislyak. The White House has indicated that Trump was alerted several weeks ago that Flynn had not accurately described the content of those calls, yet Flynn continued to serve while the counsel's office reviewed whether he had broken any laws by discussing U.S. sanctions with Kislyak.

The House Judiciary Committee on Wednesday adopted a non-binding list of oversight activities for the year, saying the committee will “continue to conduct oversight into allegations of misconduct” by executive branch officials – including any evidence that classified material had been leaked. The Republican majority on the committee rejected Democratic efforts to specifically promise an investigation of Flynn, but did agree that the committee can investigate any allegations of “improper interference” with American institutions or elections.

In a press conference Wednesday with Israeli Prime Minister Benjamin Netanyahu, Trump said Flynn was "a wonderful man" who had been mistreated by "criminal" leaks from intelligence agencies.

Contributing: Paul Singer, Herb Jackson and Nicole Gaudiano