Impeachment talk was limited to a vocal minority during President Donald Trump’s first two years in office. It grew louder earlier this year when opposition Democrats took control of the U.S. House of Representatives, where articles of impeachment originate. It endured the anticlimactic end to Special Counsel Robert Mueller’s investigation of Russian interference in the 2016 election. Throughout, Democratic leaders weren’t ready to suggest that Trump committed the “high crimes and misdemeanors” that would warrant an attempt to remove him from office. That changed after a new allegation linked Trump’s presidential actions to his own political interests, and House Speaker Nancy Pelosi announced that impeachment proceedings would begin.

1. What’s the new revelation?

During a July 25 telephone call, Trump asked Ukrainian President Volodymyr Zelenskiy to work with his personal lawyer, Rudy Giuliani, and U.S. Attorney General William Barr to “look into” former Vice President Joe Biden -- who is seeking the Democratic Party’s nomination to challenge Trump next year -- and his son, Hunter Biden. For months, Trump’s team had been alleging that Biden, while vice president, acted inappropriately to prevent an investigation into his son’s business activities in Ukraine. The call with Zelenskiy, and other factors not yet known, prompted a whistle-blower complaint from an unidentified intelligence official that congressional Democrats are demanding to see. The Trump administration released an approximate transcript of the call in a bid to show that nothing untoward had been said or promised.

2. What does Trump say?

He acknowledged bringing up with Zelenskiy “the fact that we don’t want our people, like Vice President Biden and his son,” adding to corruption in Ukraine. After the release of the call summary, Trump said it showed he’d put “no pressure whatsoever” on Ukraine to do as he asked. He’s also said, without evidence, that Biden has “done some very bad things.” Trump and congressional Republicans keep raising questions about Hunter Biden’s time on the board of Burisma Group, one of Ukraine’s biggest private gas companies, while his father was vice president.

3. What could be wrong about Trump pushing for investigation?

It at least raises the specter of the president seeking a foreign government’s help to discredit a domestic political rival. Plus, three House committees are investigating whether Trump used the withholding of congressionally approved military aid as leverage over Ukraine. Trump acknowledges ordering a halt to US$400 million in U.S. military aid to Ukraine about a week before the call, but he says it was out of frustration that European nations weren’t contributing enough to the country’s fight against Russian-backed separatists. And the summary of the July 25 call shows Trump did not explicitly tell Zelenskiy that future U.S. military assistance would be conditioned on an investigation of Biden.

4. Would this be an impeachable offense?

Congress decides that. The U.S. Constitution says the president “shall be removed from office on impeachment for, and conviction of, treason, bribery, or other high crimes and misdemeanors.” As Congress has defined it through the years, the phrase “high crimes and misdemeanors” includes exceeding or abusing the powers of the presidency, or misusing the office for improper purpose or gain.

5. What happens now?

Pelosi said she is directing six committees already investigating Trump -- Judiciary, Intelligence, Foreign Affairs, Oversight, Ways and Means, and Financial Services -- to proceed with their probes under the “umbrella” of a formal impeachment process. It is not clear which committee would ultimately recommend one or more articles of impeachment (formal written charges) to the full House. That would normally be Judiciary, but Pelosi and other Democratic leaders could name a special committee to oversee the process or move straight to a floor vote without a vote in the committee. A simple majority vote by the House, where Democrats hold 235 of the 435 seats, on any article of impeachment would send it to the Senate for consideration.

6. What would the Senate’s role be?

In one of the more unusual spectacles in American politics, the 100 members of the Senate would become the jury in a trial, with House “impeachment managers” functioning as prosecutors and the chief justice of the United States presiding. Witnesses would be called, and evidence submitted, with the impeachment managers and counsel for the accused giving opening and closing statements. If two-thirds of the senators present vote to convict -- a high bar, especially considering that Trump’s fellow Republicans hold a majority in the Senate -- Trump would be ordered removed from office.

7. Could Senate Republicans decline to consider impeachment?

Though the Constitution doesn’t specifically direct the Senate to hold a trial once the House votes to impeach, current Senate rules suggest that a trial is mandatory. They say that when the Senate is notified that House has named impeachment managers, the Senate secretary “shall immediately inform” the House that the Senate is ready to receive them and begin a trial. The Senate’s majority leader, Mitch McConnell, a Kentucky Republican, could move to change the rules in order to prevent a trial, but that would surely generate controversy.

8. How often has this happened?

The House has initiated impeachment proceedings more than 60 times, according to its historian’s office, and voted to impeach 15 federal judges, one senator, one cabinet secretary and two presidents -- Andrew Johnson in 1868 and Bill Clinton in 1998. Eight judges were convicted and removed from office.

9. How many presidents have been removed by impeachment?

Technically speaking, none. Johnson, impeached by the House for firing the secretary of war, survived because the Senate fell just one vote short of a two-thirds majority to remove him. Fifty senators voted to remove Clinton for obstruction of justice, and 45 voted to remove him for perjury, also shy of the two-thirds majority. Richard Nixon resigned the presidency in 1974 when it became clear he would be impeached by the House and convicted by the Senate. The House Judiciary Committee had approved three articles of impeachment accusing him of obstruction of justice, abuse of power and contempt of Congress, for his role in covering up the politically motivated break-in of Democratic National Committee headquarters at Washington’s Watergate office building.

10. What would happen if Trump were removed from office?

Vice President Mike Pence would automatically be elevated to the presidency. He would then appoint a vice president, subject to a majority vote in both houses of Congress. In this very hypothetical scenario, a President Pence could himself run twice for re-election, in 2020 and 2024.

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