The House will start an impeachment inquiry into President Donald Trump as a swell of Democrats denounce the president over alleged abuses of power, House Speaker Nancy Pelosi said Tuesday. Gathering pressure finally broke through the speaker's reluctance to start impeachment proceedings. Concerns have mounted about the president's efforts to push Ukraine to investigate the family of former Vice President Joe Biden, one of his top rivals for the presidency in 2020. At least 187 House members have now backed some action on impeachment, and the number ballooned this week as centrist Democrats and vulnerable freshman lawmakers joined their ranks. "The actions of the Trump presidency revealed the dishonorable fact of the president's betrayal of his oath of office, betrayal of our national security and betrayal of integrity of our elections," Pelosi said in remarks to the nation. "Therefore, today, I'm announcing the House of Representatives is moving forward with an official impeachment inquiry. I'm directing our six committees to proceed with their investigations under that umbrella of impeachment inquiry."

Pelosi announced the inquiry after huddling with key House committee chairs, the Democratic leadership team and finally her entire caucus. Her change of heart on the issue came quickly. The speaker has long called impeachment "divisive" as her party tries not to rile up Republican voters ahead of a 2020 election in which Democrats hope to keep their House majority and deny Trump a second term in the White House. Trump quickly fired off four tweets in response to Pelosi. He saw the inquiry as another Democratic attempt to unfairly target him and distract from his successes in office. The president used the familiar "witch hunt" and "presidential harassment" refrains he deployed during the investigation into Russian efforts to interfere in the 2016 election and his possible obstruction of the probe. "So bad for our country!" Trump wrote of the impeachment proceedings. Trump tweet: 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! Trump tweet 2: Pelosi, Nadler, Schiff and, of course, Maxine Waters! Can you believe this? Trump tweet 3: They never even saw the transcript of the call. A total Witch Hunt! Trump tweet 4: PRESIDENTIAL HARASSMENT! In the meeting with her caucus, Pelosi cited national security concerns in moving forward, according to NBC News. She called it a "moment of truth." The speaker also told lawmakers the House would not set up a select committee on impeachment, meaning they will keep the investigation within their standing panels. Democrats will take a rare step by starting the formal process of removing a president from office. Only three American presidents before Trump have faced serious impeachment proceedings, and Congress has never booted one from the White House. Even if Democrats eventually impeach Trump, the GOP-held Senate may never find him guilty and remove him from office. Even so, the announcement marks a dramatic turn for the Democratic-held House. Pelosi held off calls to impeach the president after the special counsel's two-year Russia probe. Her remarks Tuesday follow a confusing period when House Democratic leaders insisted they had not started the impeachment process even as some lawmakers said an inquiry had started.

U.S. House Speaker Nancy Pelosi, a Democrat from California, speaks during a news conference at the U.S. Capitol in Washington, D.C., U.S., on Tuesday, Sept. 24, 2019. Jim Lo Scalzo | Bloomberg | Getty Images