House Speaker Nancy Pelosi (D-CA) told members of Congress over the weekend that President Donald Trump’s interest in Joe Biden’s Ukraine scandals could bring about a “new stage of investigation” and ultimately impeachment.

“This violation is about our national security. The Inspector General determined that the matter is ‘urgent’ and therefore we face an emergency that must be addressed immediately,” Pelosi wrote in a letter to lawmakers on Sunday.

“If the Administration persists in blocking this whistleblower from disclosing to Congress a serious possible breach of constitutional duties by the president, they will be entering a grave new chapter of lawlessness which will take us into a whole new stage of investigation,” she continued.

According to an anonymous complaint revealed in reports last week, President Trump asked Ukrainian President Volodymyr Zelensky to look into former vice president Joe Biden’s son — Hunter Biden — and his business dealings in the eastern European country. However, according to CNN, the whistleblower “didn’t have direct knowledge of the communications,” citing an official with knowledge of the matter.

On Sunday, Trump said his conversation with Zelensky was “largely congratulatory,” adding that he did mention how he doesn’t want people like Biden and his son contributing to “the corruption already in the Ukraine.”

Trump, speaking to reporters on the White House lawn before flying to Houston, also said he doesn’t believe the person who reported the call is a “whistleblower,” stating that “you can’t have people doing false alarms like this.”

“When the president speaks to the head of another country, he has to be able to speak to those people and those people don’t want to know that they’re being recorded or that you have a stenographer working,” he said. “You don’t want to have to hear that. You can’t do that to a president and you can’t do that to other countries.”

Ukraine’s Foreign Minister Vadym Prystaiko similarly dismissed the idea of any crime or scandal in Trump’s conversation with Zelensky. “I know what the conversation was about and I think there was no pressure,” Prystaiko told Hromadske, a Ukrainian online broadcast outlet. “There was talk, conversations are different, leaders have the right to discuss any problems that exist. This conversation was long, friendly, and it touched on many questions, sometimes requiring serious answers.”

House Intelligence Committee Chairman Adam Schiff (D-CA) said Sunday that impeachment may be “the only remedy” as President Trump confirmed he discussed Biden and corruption with Ukraine’s president.

Appearing on CNN’s State of the Union, Schiff said he has been reluctant to join calls to impeach the president, but said the phone call would potentially be “the most profound violation of the presidential oath of office,” during this or any other presidency.

“If the president is essentially withholding military aid at the same time that he is trying to browbeat a foreign leader into doing something illicit that is providing dirt on his opponent during a presidential campaign, then that may be the only remedy that is coequal to the evil that conduct represents,” he said.

The UPI contributed to this report.