1. Why is impeachment getting renewed interest?

The Trump White House, resisting demands from House committees for documents and testimony from current and former administration officials, argues that Democratic lawmakers lack “any proper legislative purpose” for pursuing their inquiries. (Trump and Attorney General William Barr have said the administration’s legal strategy is aimed at protecting the power of the presidency, not protecting Trump from hard questions.) An impeachment inquiry could be seen by the courts, where these battles are being waged, as justifying the requests for information from House Democrats.

2. How exactly would impeachment begin?

A simple majority vote by the House, where Democrats hold 235 of the 435 seats, is all it would take to trigger an impeachment inquiry by the House Judiciary Committee, where Democrats outnumber Republicans 24 to 17. With or without hearings, the committee can draw up one or more articles of impeachment — formal written charges — and vote to send it to the full House, where another majority vote would send the matter for a trial in the Senate.

3. What are impeachable offenses?

Congress decides. 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.

4. What impeachable offenses could Trump be accused of?

At the moment there are two proposed impeachment resolutions sitting in the House’s in-box. One doesn’t specify a cause, while the other alleges Trump “prevented, obstructed and impeded the administration of justice” during the special counsel’s investigation of Russian interference in the 2016 presidential election. In the 2017-2018 Congress, resolutions proposed impeaching Trump for accepting what’s known as emoluments, sowing racial discord and undermining the federal judiciary. But introducing such resolutions is easy; getting a majority to support them is the challenge. (When the one blaming Trump for racial discord reached the House floor in January 2018, it was defeated 355 to 66.)

5. So will Democrats move forward on impeachment?

Until now, party leaders have mostly steered way from impeachment talk, reasoning that many voters aren’t eager to see a repeat of the warfare that raged two decades ago when Republicans sought to remove President Bill Clinton. The leader of House Democrats, Speaker Nancy Pelosi, has said she opposes pushing for impeachment because it’s clear that the Republican-majority Senate would never vote to oust Trump. (The bar in the Senate is extra high — it would take a supermajority vote of two-thirds of the senators present to convict and remove a president.) But more recently Pelosi has said that defying congressional subpoenas, as Trump is doing, “could be part of an impeachable offense.”

6. What would happen in the Senate?

In one of the more unusual spectacles in American politics, the 100 members of the Senate become the jury in a trial, with some members of the House functioning as prosecutors and the chief justice of the United States presiding (if the accused is the president). Witnesses are called, and evidence submitted, with House 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 — the official is ordered removed from office.

7. 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.

8. 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.