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.

Here's a quick summary of the latest news:

WHAT YOU NEED TO KNOW

— Two Florida businessmen tied to President Donald Trump's personal lawyer, Rudy Giuliani, and the Ukraine investigation were charged Thursday with federal campaign finance violations. The charges relate to a $325,000 donation to a group supporting Trump's reelection.

— Polls find support for impeachment has shifted significantly from earlier this year. The public is now more closely divided after earlier polls showed majority opposition to impeachment.

— Ukraine's president insisted Thursday that he faced "no blackmail" from Trump in their phone call that led to an impeachment inquiry, distancing himself from the U.S. political drama and trying to claw back his own credibility.

WHAT'S NEXT

The former ambassador to Ukraine, Marie Yovanovitch, is scheduled to appear Friday for a deposition in the House's impeachment inquiry,

NUMBERS THAT MATTER

25: The number of sitting members of the House of Representatives who so far will not be standing for reelection in 2020. That includes 20 Republicans, three of whom have already resigned from Congress.

It is unclear whether any retiring Republicans will cross party lines and vote against Trump on their way out the door. House Democrats may not need any GOP defectors to impeach Trump — an AP tally shows 227 Democrats, plus Republican-turned-independent Justin Amash of Michigan, support the inquiry that could end in articles of impeachment. Democrats need 218 votes for a measure to pass.

WORTH WATCHING

Lev Parnas and Igor Fruman were arrested on a four-count indictment that includes charges of conspiracy, making false statements to the Federal Election Commission and falsification of records. The men had key roles in Rudy Giuliani's efforts to launch a Ukrainian corruption investigation against Joe Biden and his son Hunter.

https://youtu.be/9B7cE4Av-eY