Speaker Nancy Pelosi announced on Thursday that the House of Representatives would begin drafting impeachment articles against President Trump, pushing ahead with a rapid timetable that could set the stage for a vote before Christmas to charge him with high crimes and misdemeanors.

Wrapping her announcement in the words of the Constitution and the nation’s founders, Pelosi said it had become clear over the course of two months of investigation that Trump had violated his oath of office by pressing a foreign power for help in the 2020 election. Allowing Trump to continue in office without remedy, she said, would come at “the peril of our republic”.

“His wrongdoing strikes at the very heart of our Constitution,” Pelosi said in a formal address lasting less than six minutes, delivered against a backdrop of American flags from the balcony outside her office in the Capitol. “Our democracy is what is at stake. The President leaves us no choice but to act because he is trying to corrupt, once again, the election for his own benefit.”

Pelosi’s hastily arranged announcement came a day after the House Judiciary Committee began formal impeachment proceedings against Trump, convening a hearing where three constitutional scholars invited by Democrats said Trump had engaged in conduct that clearly met the definition of impeachable offences under the Constitution. The decision follows a two-month-long inquiry by Democrats on the House Intelligence Committee that concluded that Trump abused his power by pressuring President Volodymyr Zelensky of Ukraine to announce investigations into former Vice-President Joseph R. Biden Jr. and other Democrats, while withholding a White House meeting and $391 million in vital military assistance.

“The facts are uncontested,” Pelosi said. “The President abused his power for his own personal political benefit, at the expense of our national security.”

She added: “Sadly, but with confidence and humility, with allegiance to our founders and a heart full of love for America, today I am asking our chairmen to proceed with articles of impeachment.”

Returning to the ceremonial Speaker’s hallway where she first announced in late September that Democrats were launching the inquiry, Pelosi sent a clear signal that she was confident they would have the votes they needed to impeach Trump, making him only the third President in American history to face removal by Congress.

The proceedings, unfolding less than a year before the 2020 election, will play out amid profound partisan divisions, with Democrats pressing forward amid intense Republican opposition.

Before her announcement, Trump seemed to welcome the coming fight, calling Democrats “crazy” in a pair of tweets that urged them to get the process over with quickly so he could defend himself.

“If you are going to impeach me, do it now, fast, so we can have a fair trial in the Senate, and so that our Country can get back to business,” he wrote.

Afterwards, he said Democrats were trying to “Impeach me over NOTHING”, and setting a damaging precedent. “This will mean that the beyond important and seldom used act of Impeachment will be used routinely to attack future Presidents,” he tweeted. “That is not what our Founders had in mind.”