Retired Lt. Gen. Michael Flynn, center arrives at the Trump Tower for meetings with President-elect Donald Trump on Nov. 17, 2016, in New York. / AFP PHOTO / Eduardo Munoz Alvarez

Republicans in Congress were divided Monday about whether to continue backing President Trump’s embattled national security adviser, Michael Flynn, as the controversy around him grows.

At least one Republican House member — Colorado’s Mike Coffman — called for Flynn to resign if it is proven that the retired army general intentionally misled the president.

Coffman, a retired Marine officer who is targeted by Democrats in his House releection races, said it was Flynn’s “duty to be fully transparent and forthright in his actions—anything less is unacceptable.”

He added: “If in fact he purposely misled the President, he should step down immediately.”

The Republican lawmaker’s statement came as concerns on Capitol Hill mount over whether Flynn discussed sanctions on Russia in a call with that country’s ambassador to the United States before Trump was sworn-in as president. The Post reported Monday night that the acting attorney general warned the Trump White House that Flynn could be susceptible to blackmail from the Russians because he had misled senior administration officials about his communications with the Russian ambassador.

The White House sent conflicting signals on how it was handling the situation, with top aide Kellyanne Conway signaling earlier in the day that Flynn enjoys Trump’s full confidence and spokesman Sean Spicer later indicating the president was “evaluating the situation.”

At least one top Republican — House Intelligence Committee Chairman Devin Nunes (R-Calif.) — dismissed accusations against Flynn as baseless, calling him one of the “best intelligence officers of his generation.”

“He’s being attacked maliciously by the press, which is not uncommon in this town,” Nunes said in an interview on the Fox News show “Your World with Neil Cavuto.” “I think what General Flynn is realizing is that being a general is much different than being in politics and he’s just got to work his way through it.”

Nunes and Trump ally Rep. Chris Collins (R-N.Y.) were among a small group of lawmakers to offer a full-throated defense of Flynn’s actions as the controversy swirled on Monday. Collins told reporters that Flynn should “absolutely” stay on in his current position and downplayed the seriousness of the accusations against him.

“I think some people are trying to blow this up, you know, make a mountain out of a mole hill,” Collins said. “I don’t know what was said or not but there’s nothing wrong with the national security adviser-elect, so to speak, speaking with world leaders.”

The vast majority of Republicans on Capitol Hill remained silent about the burgeoning controversy, perhaps unsure about where the president and his administration stood. The Washington Post reported that Flynn discussed sanctions against Russia with that country’s ambassador to the United States in the month before Trump was installed as president.

Neither House Speaker Paul D. Ryan (R-Wis.) nor Senate Majority Leader Mitch McConnell (R-Ky.) weighed in on the issue. But some key Republicans with seats on intelligence and defense-related panels did.

Sen. Marco Rubio (R-Fla.), one of the top Republicans on the Senate Intelligence Committee, told reporters that Flynn’s contact with the Russian ambassador will be a part of the ongoing bipartisan investigation into alleged Russian interference into the 2016 election.

“This and anything else that involves the Russians,” Rubio said. “We’re going to go wherever the truth leads us.”

Senate Armed Services Committee Chairman John McCain (R-Ariz.) said he personally has confidence in Flynn. But the senator, often a Trump critic, said he does not have enough information to make a judgment about how Flynn handled his conversations with Russia.

“I don’t know enough about this particular situation to make a comment,” McCain said.

Some said Trump’s was the only opinion that mattered.

“What’s important is if the president has confidence in the National Security Adviser,” said Senate Intelligence Committee Chairman Richard Burr (R-N.C.).

Burr’s committee is leading the Senate probe into Russian activities in 2016, including an intelligence community assessment that the country was attempting to tilt the election to Trump.

In a telephone interview with The Post on Monday, Rep. Charlie Dent (R-Pa.) declined to say whether Flynn should step down, saying he does not know what transpired beyond what he has seen in media reports.

“That’s for the administration to sort out — if he was untruthful,” Dent said. “I simply don’t know and I can’t speak to what he said.”

The centrist Republican lawmaker said he was more worried about the contours of Trump’s emerging Russia policy, which he said appears too “conciliatory.”

“I’m less concerned about Michael Flynn having conversations with the Russian ambassador than the substance of the Russian policy,”  Dent said.

Flynn’s troubles are complicated by the fact that Vice President Pence made public statements supporting Flynn’s earlier claim that he did not speak with the Russian envoy.

“He’s speaking to Vice President Pence relative to the conversation the Vice President had with Gen. Flynn and also speaking to various other people about what he considers the single most important subject there is: our national security,” Spicer said.

Flynn has been under fire since The Washington Post report revealed that he discussed sanctions with Sergey Kislyak, Russia’s ambassador to the United States, shortly before Trump’s inauguration. Flynn denied that he discussed sanctions with Kislyak both publicly and in private conversations with senior White House aides.

Sen. Lindsey O. Graham (R-S.C.) talked about the issues during a news conference with reporters in his home state.

Graham on Monday said the situation has created an issue that Flynn must address with Trump.

“He has a problem that he needs to fix with this president,” Graham told reporters. “[The national security adviser] needs to be somebody that the president trusts and it needs to be someone that America trusts.”

Graham said that he personally likes and respects Flynn but that the issue needs to be resolved quickly.

“If that conversation was misrepresented by Gen. Flynn, that needs to be corrected,” Graham said. “I’m going to leave it up to the president whether or not he believes Gen. Flynn can still serve him capably.”

For their part, Democrats have been quick to call for Flynn to either be fired or lose his security clearance. House Minority Leader Nancy Pelosi (D-Calif.) called Monday for Flynn to be let go.

“We have a National Security Advisor who cannot be trusted not to put Putin before America,” Pelosi said in a statement. “National security demands that General Flynn be fired immediately.”

Pelosi previously called for Flynn to lose his security clearance, a move endorsed by Rep. Elijah E. Cummings (Md.), the top Democrat on the House Oversight and Government Reform Committee.

“I think that’s an appropriate action,” Cummings said in an interview with ABC’s “This Week.”

Cummings said there are many unanswered questions about Flynn’s conversations with Kislyak and what, if any, security issues those conversations have created.

“Did the president instruct General Flynn to talk to the ambassador?” Cummings asked. “And did he know about it? If he knew about this conversation, when did he know it? That, to me, that is the key question. And we need to find out what that answer is.”

Sean Sullivan contributed to this report.