PORTLAND, Maine — Maine Sens. Susan Collins and Angus King said Wednesday that the Senate Intelligence Committee, of which both are members, would press for answers on former National Security Adviser Michael Flynn’s contact with Russian officials before Donald Trump becoming president.

However, neither said whether they would use the committee’s subpoena power to compel Flynn or others to testify about Russian communications with members of the Trump administration, transition team and campaign advisers.

The committee is investigating Russian meddling in the 2016 election. Collins, a Republican, and King, an independent, say they want answers from Flynn about a conversation he had with Russian Ambassador Sergey Kislyak while Barack Obama was still president. Flynn resigned Monday after it was revealed that he deceived the Trump administration, most notably Vice President Mike Pence, about his discussions with a Russian diplomat.

“There are lots of questions,” said King, who intends to grill the former general. “What contacts, if any, did he have with the Russians before the election? And on whose authority was he acting? What were his goals?”

Collins declined to be interviewed, but a spokeswoman said in a written statement, “It’s troubling if Michael Flynn, as a private citizen, was negotiating with the Russians during the campaign or even after the election, but before Donald Trump was sworn in as president.”

The committee’s investigation would “certainly” include these allegations, she said.

Trump asked Flynn to quit Monday after it became public that he misled Pence about discussing U.S. sanctions against Russia with the diplomat, administration sources told CNN. The potentially illegal discussion and subsequent deception have embroiled the Trump administration in an international controversy after less than a month in office.

Flynn could decline to speak before the committee, which is composed of seven Republicans, five Democrats and King, who caucuses with the minority party.

King said it’s too early in the process to discuss using the Senate Select Committee on Intelligence’s subpoena powers to try to order Trump advisers to answer questions.

“That is a bridge we’ll have to cross,” said King. “I’m hoping he’ll cooperate and help us get to the bottom of this.”

On Wednesday, King stressed the need for the normally secretive committee to be open.

“It’s very important for me that, as much as possible, these meetings be public,” said King.

Pence only learned that Flynn had discussed Russian sanctions earlier this month, according to multiple media reports. Trump, however, had reportedly known about it for weeks.

The conversation between Flynn and Kislyak, details of which have not been made public, was reportedly intercepted as part of U.S. intelligence’s routine monitoring of Russian officials in the country. On Jan. 26, the Justice Department, under since-fired Acting Attorney General Sally Yates, raised concerns with the president that discrepancies between Flynn’s actions and statements might make him susceptible to blackmail by Russia.

Flynn’s discussion with Kislyak might have violated the law — in addition to exposing the highest levels of American government to manipulation by an adversarial foreign power. Under the Logan Act, private citizens — which Flynn was at the time of the conversation — are barred from negotiating with foreign countries on behalf of the U.S.

If he discussed lifting sanctions, Flynn might be susceptible to prosecution, although charges would have to be brought by Attorney General Jeff Sessions.

Collins’ spokeswoman called this possibility “very troubling” but emphasized that it is not yet clear what was said. Several government officials told The Washington Post that Flynn discussed sanctions with the Russian ambassador but did not offer an explicit promise of action after Trump took office.

Members of Trump’s campaign staff and other people associated with the president were repeatedly in contact with senior Russian intelligence officials in the lead up to the election, the New York Times reported Tuesday.

“We intend to follow up on any information that comes to us involving contact between the campaign and Russia or Russian intelligence services,” said King.