Democrats on the House Judiciary Committee have asked the FBI to investigate Attorney General Jeff Sessions.
The President's senior law enforcement official has been under fire since it emerged he met Russian ambassador to the US, Sergei Kislyak, during Donald Trump's presidential campaign.
A policy adviser to the Republican candidate as Mr Trump fought for the presidency, he did not disclose the communications when he was asked at his confirmation hearing whether "anyone affiliated" with the campaign had contact with Moscow.
"We would ask the FBI and the United States Attorney's Office for Washington, DC, to take up an immediate criminal
investigation into these statements, which could potentially implicate a number of criminal laws including Lying to Congress and Perjury," a letter sent to FBI Director James Comey and US Attorney Channing Phillips read.
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Several Congressional Republicans have called on Mr Sessions to recuse himself from investigations into alleged Russian interference with the election that brought Mr Trump to power.
The President, however, said he had "total" confidence in the Attorney General as he visited Newport News in Virginia to meet sailors and shipbuilders on an aircraft carrier.
Mr Sessions told NBC News on Thursday morning he would recuse himself "whenever it's appropriate".
"There's no doubt about that," he said. "I have not met with any Russians at any time to discuss any political campaign."
Mr Sessions had meetings last year with more than 25 foreign ambassadors in his role as a member of the Senate Armed Services Committee, and had two separate interactions with the Russian ambassador, the Justice department said.
One was an office visit in the autumn, and the other happened in a group setting following a speech Mr Sessions gave in the summer.
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Paul Ryan, the House Speaker, said: "We meet with ambassadors all the time.
"I mean I did a reception about 100 yards that way with about 100 ambassadors last year. I don't even remember all the ones I met with, took pictures with.
It is really common for members of Congress to meet with ambassadors. I met with the Indian ambassador yesterday. So that kind of thing happens all the time. As to the rest of it, I would just defer you to Jeff Sessions and the Senate Judiciary committee."
But opponents want more. They say Mr Sessions has to go because he could be the subject of the investigation and that makes his position untenable.
Chuck Schumer, US Senate Democratic leader said: "The revelations that we learned about last night are extremely troubling and raise even more questions about the president and his associates' contacts with Russia.
"Did the President know about the meetings between then Senator Sessions and the Russian Ambassador? Were these the only two meetings between the now Attorney General and the Russian Ambassador and other Russian officials? Did they Attorney General disclose these meetings during the FBI background check for his nomination?
"There has been revelation after revelation, mistruth after mistruth, stories shifting like quicksand, if there is truly nothing there why won't they tell the truth?
"The bottom line is we have an obligation to get to the truth, we must evaluate the scope of Russia's interference in our election and assess if agents in their government have penetrated to the highest level of our government, nothing less than the sanctity of our dear democratic process, the primacy of rule of law, and the integrity of our executive branch is at stake."
Mr Schumer said the investigation into Russian involvment coulde be severely compromised and the only way to get to the truth was to appoint an independent investigator.
US intelligence agencies concluded last year that Russia hacked and leaked Democratic emails during the election campaign as part of an effort to tilt the vote in Trump's favour.
As Attorney General, Mr Sessions heads the Justice Department. The FBI, part of that department, has been leading investigations into the allegations of Russian meddling and any links to Trump's associates.
Mr Trump's National Security Adviser Michael Flynn was fired last month after he misled the White House about his conversations with Mr Kislyak.