U.S. Rep. Katherine Clark said on Monday that President Donald Trump's conduct "did not leave [House Democrats] a choice" but to launch an impeachment inquiry.

"When we have a president who clearly has put his own political gain over our national security, over the integrity of our elections, and over his oath of office, I think all of us felt — and the Speaker [Nancy Pelosi] included — that there was no other decision that could be made," Clark told Jim Braude on Greater Boston.

Clark first called for an impeachment inquiry into the president in July, citing Trump's "stonewalling and obstruction" into the probe into Russian interference in the 2016 election.

According to reporting from The Washington Post, House Speaker Pelosi intends for the Democratic inquiry to narrowly focus on Trump's phone call to Ukranian President Volodymyr Zelensky, in which he allegedly pressured Zelensky to investigate his political rival, former Vice President Joe Biden, and his son, Hunter Biden, and the subsequent whistleblower complaint suggesting the White House attempted a cover-up of the call.

"Right now, our focus is on how this whistleblower complaint was urgent and credible. We are focusing right now on the intelligence committee and their work in this particular complaint, but the speaker was clear: This impeachment inquiry extends to all the six relevant oversight committees," Clark said.

"We will have to see how the facts progress," she added.

Clark also addressed the president's comments from earlier Monday afternoon, when Trump told reporters outside the Oval Office that he was trying to determine the identity of the whistleblower. In a tweet Monday morning, he also seemed to call for Rep. Adam Schiff, the chairman of the House Intelligence Committee, to be arrested for treason.

Clark said she believed Trump's tweets were "threatening not only the whistleblower, but those who have given the whistleblower credible information," and added that the accusations of treason were "dangerous."

"It is dangerous to say things, to make accusations of treason," she said. "It is dangerous to solicit political favors and investigations from a country depending on you for their security."

"That is why we have to act," she continued.