The impeachment managers will present the House's case at the Senate trial and the articles cannot be transmitted without managers being named.
Pelosi said she needs to know the structure of the Senate trial before naming the managers, but said what she's heard so far sounds unfair, echoing the complaints of Senate Democratic Leader Chuck Schumer, who has been rebuked after he asked for acting chief of staff Mick Mulvaney and Mulvaney's assistant to testify.
"We cannot name managers until we see what the process is on the Senate side, and I would hope that that will be soon," Pelosi said. "So far we haven't seen anything that looks fair to us, so hopefully it will be fairer and when we see what that is, we'll send our managers."
Pelosi also appeared noncommittal when a reporter asked if it was possible that the House might avoid sending the articles over to the Senate.
"We're not having that discussion. We have done what we have set out to do. The House has acted on a very sad day to protect and defend the Constitution of the United States," she said. "So, we will make our decision as to when we're going to send when we see what they're doing on the Senate side, but that's a decision that we will make jointly."
When asked if she could guarantee that the articles would at some point be sent to the Senate, Pelosi said, "That would have been our intention but we'll see what happens over there."
"I said we're not sending it tonight because it's difficult to determine who the managers would be until we see the arena in which we will be participating," the House speaker said. "That's all I said. I never raised the prospect -- we'll see when they come forward. It's up to the Senate to say what their rules will be. My colleagues didn't want to say anything about this because it is, you know, this is a serious matter."
She also alleged that Senate Majority Leader Mitch McConnell was "in cahoots with the lawyers of the accused." McConnell said he will "speak about House Democrats' precedent-breaking impeachment" at 9:30 a.m. Thursday on the Senate floor.
He was also scheduled to meet with Schumer on Thursday, though that was prior to the articles being passed.
The speaker's comments came just moment after the Democrat-led House voted to approve two articles of impeachment accusing Trump of abuse of power and obstruction of Congress, making him the third U.S. president to ever be impeached.
The Senate trial will most likely begin next month.