Impeachment inquiry: Here's what it means and what happens now

House Speaker Nancy Pelosi ordered an impeachment inquiry of President Donald Trump after an intelligence community whistleblower came forward with a complaint last month reportedly relating to Trump’s communications with the president of Ukraine. In her announcement of the official inquiry, Pelosi accused the president of “betrayal of his oath of office and betrayal of our national security and betrayal of the integrity of our elections.”

But what happens now?

The House has initiated impeachment proceedings more than 60 times in U.S. history, but less than a third of those cases have resulted in full impeachments.

Only two presidents have been impeached: Andrew Johnson in 1868 and Bill Clinton in 1999. Both won acquittal in the Senate.

Richard Nixon, who was the subject of impeachment proceedings, resigned from office in 1974 when it looked certain that the House would impeach him and his prospects in the Senate appeared dire.

Here’s what impeachment proceedings entail and what to expect as the House moves forward with its impeachment inquiry against Trump.

Impeaching a president is often misunderstood to mean his removal. It actually means the House has voted to bring one or more articles of impeachment and send the process forward. No president has been ousted by impeachment.

As laid out in the Constitution, the House of Representatives possesses the sole power to impeach, while the Senate acts as the sole court for impeachment trials and the Chief Justice of the Supreme Court presides over the trial.

Before the House authorizes an impeachment inquiry, the House Judiciary Committee typically conducts an investigation in which it holds hearings on proposed articles of impeachment and votes on whether to approve them. If the committee votes to pass the articles, they are then passed on to a vote by the full House.

If the full House votes to approve any of the presented articles, those articles are then sent to the Senate to go to trial.

The Senate, however, is not obligated to take these articles to trial.

In Trump’s case, there is a distinct possibility that the Republican-controlled Senate will refuse to try the case presented by the House. Senate Majority Leader Mitch McConnell, R-Ky., has shown in the past that he is not particularly beholden to expectations, such as his refusal to hold a hearing on Supreme Court nominee Merrick Garland, who was nominated by former-President Barack Obama.

If the Senate does take the presented articles of impeachment to trial, the House appoints members by resolution to manage the ensuing trial on its behalf. These members effectively act as the prosecutors in the trial and tend to be selected from the Judiciary Committee.

After the trial — which can sometimes last for months — the Senate holds a vote. A two-thirds majority is required for a conviction, which would result in the official in question being removed from office.

So, what happens next in the inquiry against Trump?

Now that House Speaker Nancy Pelosi has launched a formal inquiry, the House Judiciary Committee will need to decide which articles of impeachment to recommend. Though the committee will likely focus on matters related to Ukraine, it’s possible that the articles could be in relation to other matters as well.

Some Democrats in Congress have long wanted to kick-start the constitutional process to remove Trump, despite the slim odds of success. But they lacked a critical mass and Pelosi's support.

Trump's machinations to avoid culpability from the Russia investigation fed into their push, but that inquiry came to an indistinct conclusion, with troubling episodes of presidential behavior uncovered by special counsel Robert Mueller but no charges recommended for obstructing justice or conspiring with Moscow in its audacious efforts to tip the 2016 U.S. election to Trump.

Trump's pre-election payment to a porn actress to maintain her silence and apparent Trump Organization profiteering from his presidency also fueled impeachment sentiment from a segment of the party. But it took a whistleblower's still-secret complaint about Trump's dealings with Ukraine to change the landscape.

This story was reported from Los Angeles. The Associated Press contributed.