Pelosi announces formal impeachment inquiry of Trump
House Speaker Nancy Pelosi (D-Calif.) announced on Sept. 24 that the House would begin impeachment inquiry of President Trump. 
House Speaker Nancy Pelosi on Tuesday announced a formal impeachment inquiry into President Trump, a dramatic turnaround by the Democratic leader that sets up a constitutional and political clash pitting the Congress against the nation’s chief executive.
“The actions of the Trump presidency have revealed the dishonorable fact of the president’s betrayal of his oath of office, betrayal of our national security and betrayal of the integrity of our elections,” Pelosi said in brief remarks. “Therefore, today, I am announcing the House of Representatives is moving forward with an official impeachment inquiry.”
Impeachment is a rare and extraordinary first step that could lead to overturning the decision of U.S. voters in 2016 to elect Trump. Pelosi’s decision foreshadows an intensely partisan fall, triggering pushback from Trump allies with repercussions for the 2020 campaign.
The president immediately lashed out on Twitter.
“Such an important day at the United Nations, so much work and so much success, and the Democrats purposely had to ruin and demean it with more breaking news Witch Hunt garbage. So bad for our Country!” he wrote.
Pelosi’s change of heart comes after days of consulting allies and follows reports that Trump may have pressured a foreign leader to investigate former vice president and potential 2020 campaign rival Joe Biden and his family.
How does impeachment work?
House Democrats began a formal impeachment inquiry of President Trump on Sept. 24. Here's how the impeachment process works. 
Those reports over a seven-day period created a groundswell of support among Democrats for impeachment, with moderates from swing districts joining liberals in calling for an inquiry.
Trump, meanwhile, said that he has authorized the release of the full transcript of his phone call with the Ukrainian president in which Trump is said to have brought up investigating Biden and his son.
“I am currently at the United Nations representing our Country, but have authorized the release tomorrow of the complete, fully declassified and unredacted transcript of my phone conversation with President Zelensky of Ukraine,” Trump tweeted Tuesday afternoon.
“You will see it was a very friendly and totally appropriate call. No pressure and, unlike Joe Biden and his son, NO quid pro quo! This is nothing more than a continuation of the Greatest and most Destructive Witch Hunt of all time!”
Trump has admitted publicly that he asked Ukraine President Volodymyr Zelensky to probe Biden’s son, who has connections to a business that was under investigation. But he said no pressure was involved. However, The Washington Post has reported that Trump asked his staff to put a freeze on military assistance to Ukraine at least a week before he made the request to Zelensky.
Biden on Tuesday called for Congress to begin impeachment of Trump if the White House continues to stonewall congressional investigations, including questions regarding reports that Trump asked the Ukrainian president to investigate Biden and his son, Hunter.
“I can take the political attacks. They’ll come and they’ll go, and in time they’ll soon be forgotten. But if we allow a president to get away with shredding the United States Constitution, that will last forever,” Biden said in brief remarks Tuesday afternoon in Wilmington, Del.
The House plans to vote Wednesday on a resolution disapproving of the Trump administration’s efforts to block the release of the complaint and the need to protect the whistleblower.
“This is not a partisan matter, it’s about the integrity of our democracy, respect for the rule of law and defending our Constitution,” Pelosi and House Majority Leader Steny H. Hoyer (D-Md.) said in a statement.
Impeachment has only occurred twice in U.S. history — against Presidents Andrew Johnson and Bill Clinton. Neither man was removed from office. President Richard M. Nixon resigned in 1974 rather than face a House vote on impeachment.
Even if the House votes to impeach Trump, his ouster would require a conviction in the Senate, where Republicans have rallied to the president’s defense.
Senate Majority Leader Mitch McConnell (R-Ky.) declined to say Tuesday what he would do if the House voted for impeachment.
In the House, a tranche of Democrats who opposed impeachment have been coming out in favor of impeachment over the past 48 hours. That total that now exceeds 160 out of 235, according to a Post analysis.
Rep. John Lewis, an influential member in the caucus, was one of the latest Democrats to back impeachment on Tuesday. The Georgia Democrat, a staunch Trump critic and close Pelosi ally, had declined for months to weigh in on impeachment out of respect for the speaker.
“There comes a time when you have to be moved by the spirit of history to take action to protect and preserve the integrity of our nation. I believe, I truly believe, the time to begin impeachment proceedings against this president has come,” Lewis said on the House floor. “To delay or to do otherwise would betray the foundation of our democracy.”
Pelosi had been considering the creation of a select committee to conduct the inquiry, but decided the House Judiciary Committee, which has the authority, would handle the investigation.
Pelosi had been reluctant to endorse impeachment, resisting the extraordinary step for months despite pressure from the party’s liberal base and several 2020 Democratic presidential candidates. She has argued that neither the public nor the Republican Party, which controls the Senate, supports impeachment and that pursuing the matter could prove politically costly to the moderate Democrats who helped deliver the House majority last year.