Independent Sen. Angus King of Maine said Tuesday evening Donald Trump could be held responsible for obstruction of justice if an allegation about the president persuading former FBI Director James Comey to end investigation into Michael Flynn’s Russia connections turns out to be true. King also said the allegation could also pave way for Trump’s impeachment.

Earlier in the day, Trump told Comey to let go of the investigation against the former national security adviser over the latter's links to Russia, the New York Times reported, citing a February memo written by Comey. The conversation between Trump and Comey happened in a meeting at the Oval Office, a day after Flynn resigned.

“I hope you can see your way clear to letting this go, to letting Flynn go,” Trump told Comey, the Times reported. “He is a good guy. I hope you can let this go.”

However, the White House denied any such allegation.

“While the president has repeatedly expressed his view that General Flynn is a decent man who served and protected our country, the president has never asked Mr. Comey or anyone else to end any investigation, including any investigation involving General Flynn,” the White House said in a statement. “The president has utmost respect for our law enforcement agencies and all investigations. This is not a truthful or accurate portrayal of the conversation between the president and Mr. Comey," the statment added.

But, if the allegation is true, it may bring lawmakers “closer to the possibility of yet another impeachment process," King told CNN.

“If that's true and confirmed, I think you're getting very close to the legal definition of obstruction of justice,” King said. “Reluctantly, I have to say yes, because obstruction of justice is a serious offense," he further added.

“I say it with sadness and reluctance. This is not something I have advocated for, or the word has not passed my lips in this whole tumultuous three or four months,” the Senate intelligence committee member who caucuses with Democrats said, adding: “If indeed the president tried to tell FBI director who worked for him that he should drop an investigation, whether it was Michael Flynn or whether it was some investigation that had nothing to do with Russia or politics or the election. That’s a very serious matter.”

Obstruction of justice is defined as any conduct in which a person deliberately interferes with the administration of justice. People are charged under this decree based on allegations that a defendant tried to get in the way of an official proceeding by either destroying evidence or interfering with the duties of jurors or court officers.

Trump has also been facing flak over the abrupt removal of Comey on May 9, which the president said was because of the latter’s handling of investigation into Democrat Hillary Clinton’s email scandal. Democrats speculated whether Comey's dismissal was because of the FBI investigation he led into ties between the president’s associates and Russia during the presidential campaign. However, the White House denied any such speculation.