When asked at her weekly news conference if there’s risk in Republicans saying she is playing games by holding the articles, Pelosi said, "We don't know the arena that we're in. Frankly, I don’t care what the Republicans say.”
“We would hope there would be a fair process just as I hope they would honor the Constitution,” Pelosi said of Republicans, adding that she’s said all she’s going to say on the matter until she knows more about what Senate Majority Leader Mitch McConnell will agree to.
Notably, she has not said what exactly she needs to see from the Senate and it's still not clear if the Democrats’ demand for live witnesses will be a deal-breaker.
"In any event, we are ready. When we see what they have, we'll know who, and how many [impeachment managers], we'll send over. And that's all I have to say on this now,” Pelosi said.
As Pelosi spoke, Trump tweeted, "Pelosi feels her phony impeachment HOAX is so pathetic she is afraid to present it to the Senate, which can set a date and put this whole SCAM into default if they refuse to show up! The Do Nothings are so bad for our Country!"
McConnell, speaking on the Senate floor a short time before Pelosi, said that she and her fellow Democrats were getting "cold feet" and were "afraid" to send their "shoddy" articles of impeachment to the Senate.
The Constitution's framers suspected that "we might might have rogue president," Pelosi said. "I don't think they suspected that we'd have a rogue president and a rogue leader in the Senate at the same time," Pelosi shot back.
McConnell later sought out reporters to say, "It's beyond me how the speaker and the Democratic leader in the Senate think withholding the articles of impeachment and not sending them over gives them leverage - is beyond me. Frankly, I'm not anxious to have the trial, if she thinks her case is so weak she doesn't want to send it over, throw me into that briar patch.”
Pelosi began her news conference began by praising her Democratic caucus for voting to impeach President Trump, saying it was interesting to see the bipartisan response.
“I have a spring in my step because of the moral courage of our caucus,” she said.
A short time later, after about a 40-minute meeting with Pelosi, Senate Minority Leader Chuck Schumer emerged to say the two were united on their approach to impeachment.
“What she said was just right,” Schumer said of the speaker’s presser earlier, adding, “We are on the same page.”
McConnell late Thursday said he had a "cordial" meeting with his Democratic counterpart over how the Senate would proceed with a trial, but said "we remain at an impasse."
McConnell has resisted a demand from Minority Leader Chuck Schumer and other Democrats that a Senate trial must include live witnesses or wouldn't be "fair" or "real."
House Minority Leader Kevin McCarthy on Thursday accused Pelosi of "admitting defeat" by not committing to transmitting the impeachment articles to the Senate.
"She's so embarrassed by it, she won't send the papers over," he said. "She's admitting defeat by not sending it. By refusing to send impeachment over, she knows the outcome is not good."
"At the end of the day the American public needs to move on," he said.
"I would think that if Nancy Pelosi thought impeachment was so important ... I thought she would have welcomed questions on impeachment," he said
Speaking after the House impeachment vote Wednesday night, Pelosi would not commit to formally sending the articles of impeachment to the Senate – a requirement ahead of any impeachment trial. “That would have been our intention,” she said at a news conference with her six investigative chairs. “We’ll see what happens over there.”
Pelosi said the House wouldn’t name impeachment managers – the term used to describe the team of House members selected to present the impeachment case to the Senate – “until we see what the process will be on the Senate side.”
Earlier in the week, House Majority Leader Steny Hoyer suggested Democrats weren’t considering the idea.
“I don't think that that's the path we'll follow, but that does not mean we will immediately deliver. There are considerations relating to other legislation,” he said. “As I understand the rules of the Senate, once they receive the articles they have to act, they have to go into trial, they can't do any other work. So that will play into that consideration.”
But the possibility of withholding the articles to maintain leverage over the terms of a Senate impeachment trial has picked up steam among progressives.
Rep. Earl Blumenauer, D-Ore., speaking in favor of impeachment on the House floor Wednesday, said he hoped Democratic leaders withheld articles until they “can negotiate an agreement on process and witnesses from McConnell so that the next stage will be open and fair, so that Donald Trump will ultimately be held accountable.”
“There is no requirement that we transmit the articles immediately, and especially when there is no agreement from the Senate about exactly what the trial is going to look like,” Rep. Pramila Jayapal, D-Wash., a co-chair of the Congressional Progressive Caucus, told ABC News.
“This is a very different situation than the last impeachment, when you definitely saw Democrats and Republicans at least trying to work together on what the rules would be,” she said. “If Republican senators want to have any legitimacy in the future … then they need to make sure this is a real trial."
An official working on the Trump administration’s impeachment defense told ABC News that Pelosi withholding the articles from the Senate amounted to “a complete gimmick.”
“I think this is obviously an indication that unless Speaker Pelosi and her colleagues think they could rig a process, that they’ll actually feel strong enough about bringing their case forward,” said Tony Sayegh, a former spokesman for the Treasury Department who is serving in a special communications advisory role with the White House’s impeachment defense team.
Asked if there was any specific action or response the White House had to Pelosi’s position, Sayegh would not say.
ABC's Trish Turner. Mariam Khan and Ben Gittleson contributed to this report.