For only the fourth time in U.S. history, the House of Representatives has started a presidential impeachment inquiry . House committees are trying to determine if President Donald Trump violated his oath of office by asking a foreign country to investigate a political opponent.

A quick summary of the latest news:

WHAT YOU NEED TO KNOW

House Intelligence Committee Chairman Adam Schiff, D-Calif., returns to the secure area at the Capitol where former U.S. Ambassador William Taylor, is testifying in the impeachment investigation of President Donald Trump, in Washington, Tuesday, Oct. 22, 2019. (AP PhotoJ. Scott Applewhite)

House Intelligence Committee Chairman Adam Schiff, D-Calif., returns to the secure area at the Capitol where former U.S. Ambassador William Taylor, is testifying in the impeachment investigation of President Donald Trump, in Washington, Tuesday, Oct. 22, 2019. (AP PhotoJ. Scott Applewhite)

— Democratic lawmakers say former U.S. Ambassador William Taylor, a diplomat who has sharply questioned President Donald Trump's policy on Ukraine, provided lawmakers with a "disturbing" account of events at the center of the impeachment probe.

— President Donald Trump triggered outrage Tuesday by comparing the Democrat-led impeachment inquiry to a lynching, assigning the horrors of a deadly and racist chapter in U.S. history to a process laid out in the Constitution.

— Behind closed doors, President Donald Trump has made his views on Ukraine clear: "They tried to take me down." The president, according to people familiar with testimony in the House impeachment investigation, sees the Eastern European ally, not Russia, as responsible for the interference in the 2016 election. It's a view denied by the intelligence community.

WHAT'S NEXT

Laura Cooper, deputy assistant secretary of defense for Russia, Ukraine and Eurasia, is scheduled to testify on Wednesday. She has responsibility at the department for policy concerning Russia and Ukraine and has served at the Defense Department since 2001.

NUMBERS THAT MATTER

In an impeachment, the Senate becomes a trial court weighing the charges against a president. It takes 67 senators to convict a president and remove him from office. The Senate currently has 53 Republicans and 45 Democrats, plus two independents who caucus with the Democrats.

If every Democrat and independent were to vote against Trump, 20 GOP defectors would still be needed for a conviction. And while 23 Republican-held seats are up for election in 2020, most are in states Trump won. So far there are no signs of such a mass defection.

WORTH WATCHING

Trump ignited a firestorm Tuesday when he described the impeachment probe as a "lynching." See some of the reactions on Capitol Hill, from Trump defenders to staunch critics:

https://youtu.be/NhOgu_Pvzf4