WASHINGTON — U.S. Sen. Susan Collins joined a chorus of calls for Attorney General Jeff Sessions to step back from investigations into Russian meddling in the 2016 election after officials confirmed meetings with the Russian ambassador that Sessions didn’t disclose during his confirmation hearing.

During a hastily called news conference Thursday afternoon, Sessions said he would recuse himself from any investigation related to the 2016 presidential campaign, which would include any Russian interference in the electoral process.

Sessions said he had met with department ethics officials soon after being sworn in last month to evaluate the rules and cases in which he might have a conflict.

“They said that since I had involvement with the campaign, I should not be involved in any campaign investigation,” Sessions said. He added that he concurred with their assessment, and would thus recuse himself from any existing or future investigation involving Trump’s campaign.

Sessions said discussions about his recusal began before the revelation of his meetings with the Russian ambassador. He said he and ethics officials had agreed on Monday to meet for a final time Thursday.

The previously undisclosed discussions while Sessions was an Alabama senator and surrogate for President Donald Trump sparked a range of reactions earlier Thursday.

Collins, a friend of Sessions who introduced him at his confirmation hearing, said in a statement that he “should recuse himself to ensure public confidence” in investigations into Russian interference and “clarify his statements to the Judiciary Committee with respect to his communications with the Russian ambassador.”

U.S. Rep. Chellie Pingree, a Democrat from Maine’s 1st District, went further in her criticism of Sessions on Thursday, calling on him to resign because “his clear disregard for the truth demonstrates that he is unfit” to serve as attorney general.

“As the nation’s top attorney, Jeff Sessions should be held to the highest standards and know that lying under oath constitutes perjury,” she said in a statement.

U.S. Sen. Angus King, a Maine independent who caucuses with Democrats, had already asked Sessions to recuse himself. In a Thursday statement, he called for Sessions to go back before the Judiciary Committee to “clarify his original remarks, which do not appear to be factual, and to fully explain this inconsistency.”

And U.S. Rep. Bruce Poliquin, a Republican from Maine’s 2nd District, said Thursday afternoon that “it would be appropriate for [Sessions] to recuse himself” from Justice Department investigations since Americans “must have confidence in the integrity and impartiality” of them.

One of the two meetings was a private conversation between the former senator and Russian Ambassador Sergey Kislyak that took place in September in Sessions’ Senate office, at the height of what U.S. intelligence officials say was a Russian cybercampaign to upend the U.S. presidential race.

When Sessions spoke with Kislyak in July and September, the senator was a senior member of the influential Armed Services Committee as well as one of Trump’s top foreign policy advisers. Sessions played a prominent role supporting Trump on the stump after formally joining the campaign in February 2016.

At his Jan. 10 Judiciary Committee confirmation hearing, Sessions was asked by Sen. Al Franken, D-Minnesota, what he would do if he learned of any evidence that anyone affiliated with the Trump campaign communicated with the Russian government in the course of the 2016 campaign.

“I’m not aware of any of those activities,” Sessions responded. “I have been called a surrogate at a time or two in that campaign and I did not have communications with the Russians.”

Sessions defended his comment on meetings with Russian officials to Franken as “honest and correct as I understood it at the time,” though he also said he would “write the Judiciary Committee soon — today or tomorrow — to explain this testimony for the record.” His explanation, he said, was that he was “taken aback” by Franken’s question — which referenced a breaking news story about contacts between Trump surrogates and Russians.

“It struck me very hard, and that’s what I focused my answer on,” he said. “In retrospect, I should have slowed down and said I did meet one Russian official a couple times. That would be the ambassador.”

The congressional backlash against Sessions did not sway Trump, who said Thursday afternoon that he has “total confidence” in the attorney general.

Speaking aboard the aircraft carrier USS Gerald Ford in Newport News, Virginia, Trump told reporters that he was not aware of Sessions’ contact with the Russian ambassador. Trump also said that Sessions “probably” testified truthfully during his confirmation hearing last month before the Senate Judiciary Committee.

Asked earlier Thursday whether Sessions should recuse himself, Trump added: “I don’t think so.”

Officials said Sessions did not consider the conversations relevant to the lawmakers’ questions and did not remember in detail what he discussed with Kislyak.

“There was absolutely nothing misleading about his answer,” Sarah Isgur Flores, Sessions’ spokeswoman, said.

On Thursday, though, Sessions outlined fairly extensive details of the encounter, which also included two senior Sessions staffers. He said he talked with the ambassador about a trip he made to Russia in 1991, terrorism and Ukraine — a major policy issue after Russia’s annexation of Crimea and the imposition of U.S. and European Union sanctions on Russia for its actions.

At one point, Sessions said, “it got to be a little bit of a testy conversation.” He said the ambassador invited him to lunch, but he did not accept.

“Most of these ambassadors are pretty gossipy, and this was in the campaign season, but I don’t recall any specific political discussions,” Sessions said.

In January, Sen. Patrick Leahy, D-Vermont, asked Sessions for answers to written questions. “Several of the President-elect’s nominees or senior advisers have Russian ties. Have you been in contact with anyone connected to any part of the Russian government about the 2016 election, either before or after election day?” Leahy wrote.

Sessions responded with one word: “No.”

In a statement issued Wednesday night, Sessions said he “never met with any Russian officials to discuss issues of the campaign. I have no idea what this allegation is about. It is false.”

Justice officials said Sessions met with Kislyak on Sept. 8 in his capacity as a member of the armed services panel rather than in his role as a Trump campaign surrogate.

“He was asked during the hearing about communications between Russia and the Trump campaign — not about meetings he took as a senator and a member of the Armed Services Committee,” Flores said.

She added that Sessions last year had more than 25 conversations with foreign ambassadors as a senior member of the Armed Services Committee, including the British, Korean, Japanese, Polish, Indian, Chinese, Canadian, Australian and German ambassadors, in addition to Kislyak.

In the case of the September meeting, one department official who came to the defense of the attorney general said, “There’s just not strong recollection of what was said.”

The Russian ambassador did not respond to requests for comment about his contacts with Sessions.

“After lying under oath to Congress about his own communications with the Russians, the Attorney General must resign,” House Minority Leader Nancy Pelosi, D-California, said in a statement, adding that “Sessions is not fit to serve as the top law enforcement officer of our country.” On Thursday, more than 100 House Democrats followed suit. Every Democrat on the House Judiciary Committee also called for a criminal investigation of Sessions’ comments during his confirmation hearing.

In an acknowledgment that Sessions is unlikely to step down, Senate Minority Leader Chuck Schumer and other Democrats focused mostly on ensuring impartial investigations of Russian meddling in U.S. elections.

“Better for the country if he resigns, but let’s get an investigation going,” he said.

Schumer also said that the Justice Department’s inspector general should investigate whether Sessions made any attempts to thwart any ongoing Russia-related investigations. If lawmakers were not satisfied with the choice of independent counsel, Democrats would seek to revive an expired independent counsel law, but would rewrite it to empower a three-judge panel like the D.C. Circuit Court — not the attorney general — to appoint the special prosecutor.

Some Democratic senators called on Sessions to appear again before the Judiciary Committee to explain his relationship and conversations with Russian officials under oath. Others are encouraging congressional tax-writing committees to use their authority to review Trump’s tax returns for any sign of Russian connections.

Sen. Lindsey Graham, R-South Carolina, said at a CNN town hall Wednesday night that if the substance of Sessions’ conversations with the Russian ambassador proved to be improper or suspect, he too would join the call for Sessions to go.

“If there is something there and it goes up the chain of investigation, it is clear to me that Jeff Sessions, who is my dear friend, cannot make that decision about Trump,” Graham said, although he stressed Sessions’ contacts with the Russian ambassador could have been “innocent.”

Washington Post writers Julie Tate, Robert Costa, Karoun Demirjian, Ed O’Keefe, Sari Horowitz and Matt Zapotosky and BDN writers Michael Shepherd and Christopher Burns contributed to this report.