Washington (CNN)An impeachment net is fast closing around President Donald Trump, with the House of Representatives poised to cast its highly symbolic first vote Thursday in the Democratic bid to oust the President.

A domino effect of developments that appeared to threaten Trump emphasized the momentum of the impeachment drive on the eve of the vote, amid unsuccessful efforts by Republicans on Capitol Hill to gum up the process.

Thursday promises to be an even more consequential day, since new testimony is expected from a key White House insider and proceedings in several court cases could further unglue the President's defense.

The full House will be asked to pass a resolution setting out the rules and terms of the impeachment inquiry. The measure provides for open hearings and a written report on the case, and permits Trump to be represented by counsel and minority Republicans to subpoena their own witnesses with the majority's agreement.

The vote will mark a new peak in the confrontation between the President and House Speaker Nancy Pelosi -- the two most powerful politicians in Washington -- both of whose careers could be on the line in the impeachment fight.

Pelosi resisted impeachment demands from liberals in her caucus for months during the controversy over Russian election interference. But she has moved fast against the President since the Ukraine scandal burst into the open, even though the showdown could have unpredictable political consequences, especially if it spills into an election year.

"Mr. Clyburn, our whip, has given me a very good report about our vote tomorrow. He's the whip, the vote counter. Thank you, Mr. Clyburn," Pelosi said at an event in Washington on Wednesday night.

The vote could be a tough one for a small corps of Democrats who have yet to back impeachment and for party lawmakers from districts that Trump won in 2016 but that helped Democrats grab back the House last year. It will also give Republicans a chance to make a political point to voters back home by standing with the President -- who remains wildly popular among GOP base voters.

The White House is digging in, insisting that Trump did nothing wrong, as the widening contours become clear of a scandal sparked by accusations that he abused his power by seeking political favors from Ukraine.

Full story at https://edition.cnn.com/2019/10/31/politics/donald-trump-impeachment-democrats/index.html