Trump has branded the case a "hoax" and a "witch hunt" but the White House is girding for a trial that could present damaging evidence against the United States leader on national television over two weeks or more.
Bolton is believed to have firsthand knowledge of Trump's dealings with Ukraine and why the administration temporarily withheld almost $400 million in military assistance from the USA ally. Other candidates, including former Vice President Joe Biden, will have the state to themselves.
But Pelosi, D-Calif., hasn't announced the precise timing for a House vote on that resolution, which would formally set the stage for a Senate trial as early as this week.
However, immediate dismissal without a trial appeared to lack votes needed to pass in the Senate, with a handful of Republican Senators rejecting Trump's suggestion on Monday.
Republicans enjoy majority in the 100-member Senate.More news: Issa Rae Epically Shades This Year’s Oscar Nominees
"It's about a fair trial", Ms Pelosi told ABC's This Week.
A key question looming over the trial is to what extent the president will seek to influence the proceedings and limit witnesses who have direct knowledge of events at the center of the inquiry.
Trump told Fox News in an interview last week that he had "no problem" with Bolton and other officials providing testimony but that he'd likely invoke executive privilege if the situation were to arise. No evidence of wrongdoing by the Bidens has emerged.
White House officials are growing increasingly concerned that at least four Republican senators will agree to Democrats demands to call high-profile witnesses who may bolster some of the underlying details that House Democrats claim proves that the president's conduct was impeachable.
Senator Susan Collins, one of those at-risk GOP lawmakers, said she's been working with a small group of Republicans to ensure the upper chamber hears from additional witnesses.
© J. Scott Applewhite, AP House Speaker Nancy Pelosi, D-Calif., shown speaking to reporters January 9, 2020, meets with the Democratic Caucus Tuesday to discuss next steps in the impeachment of President Donald Trump.More news: Australian Open qualifying player collapses on court as bushfire smoke chokes Melbourne
But Pelosi's allies framed the delay as a win, arguing that the time in limbo allowed the public to see that Senate Republicans are tilting the rules of the impeachment trial to benefit the president.
It takes just 51 votes during the impeachment trial to approve rules or call witnesses. If that succeeds, he said Republicans likely will want to call witnesses of their own. He was said to have compared the Ukraine actions to a "drug deal" he wanted no part of and warned that Giuliani was a "hand grenade" about to go off.
However, that's unlikely. People close to Trump have urged against this, as Giuliani is a focus of the impeachment probe for the work he did as it relates to Ukraine. Mr. Bolton had refused to comply with the House inquiry past year.
"Let's be optimistic about the future ... a future that will not have Donald Trump in the White House, one way or another".
"In conversations with Republican colleagues, especially after the briefing last week, they were discouraged that the attitude that was being communicated to us that Congress is an annoyance" and they only wanted to provide "morsels of information", Kaine said.More news: Confirmed: Billie Eilish to perform next Bond theme song