The leaders puffed up their chests on Thursday morning in the wake of the House’s Wednesday vote to impeach the president. McConnell called it “slapdash” and said the precedent being set means “future Houses of either party will feel free to toss up a ‘jump ball’ every time they feel angry. Free to swamp the Senate with trial after trial.”

Schumer shot back, saying “we believe the House’s case is strong, very strong…but if the Republican leader believes it’s so weak, why is he so afraid of relevant witnesses and documents?”

While it was not imperative the two leaders strike an agreement on Thursday, making progress in the coming days would go a long way to establishing some stability in the chamber, particularly after Speaker Nancy Pelosi (D-Calif.) said she would not immediately send over the impeachment managers to trigger the trial.

Senators right now don’t know when the trial will begin, how long the debate time will be, whether witnesses will be called and whether they can also consider legislation during the trial.

Perhaps, some hope, Schumer and McConnell can cut a deal on the absolute basics and give the trial a veneer of bipartisanship.

“I’m gonna be optimistic. They should. It would be helpful. There’s no reason we can’t agree on what to do the first couple of weeks. That’s what we should do,” said Sen. Lamar Alexander (R-Tenn.). “We ought to agree on how to begin … and then we can stop and say: Do we need more evidence? And then we’ll probably disagree on that.”

But Schumer’s caucus seems to fully back his witness requests and worries that if McConnell doesn't agree to witnesses now, Republicans will never help call them.

“We should have had it worked out now,” said Sen. Joe Manchin (D-W.Va.). “You’ve got to have evidence. You’ve got to have witnesses … some people would speculate you would do one and not the other. So there has to be an agreement” that touches on witnesses.

But Schumer’s aim to negotiate witnesses and debate time at the same time and McConnell’s opposition made it impossible, for both sides to clinch a deal and save face on Thursday.

“From what I’ve seen on TV it doesn’t look very cheery right now. But they’re pros. They can put their differences aside,” said Sen. Jon Tester (D-Mont.).

“It’s a strained relationship,” acknowledged a senator who speaks to both leaders regularly.

Schumer also met with Pelosi Thursday to discuss strategy. Shortly after the House impeached Trump Wednesday night, Pelosi refused to commit to sending McConnell the articles charging abuse of power and obstruction of Congress, arguing that Democrats “haven’t seen anything that looks fair to us.”

But McConnell seemed unmoved by her threat.

“It’s like the prosecutors are getting cold feet in front of the entire country and second-guessing whether they even want to go to trial,” McConnell said in a 30-minute floor speech on Thursday morning.

Some liberals have argued that Pelosi has leverage over McConnell, arguing she can withhold sending impeachment managers to the Senate to pressure him into negotiating with Schumer.

Schumer says his Sunday letter to McConnell asking for administration witnesses was merely a response to McConnell's public statements about working with Trump and his repeated predictions that the Senate would acquit him. He asserted on Thursday that "Democrats want a fair trial" and that McConnell currently "has no intention of conducting a fair trial."

“Look, I will always be open and I'm not going to let anything personal get in the way,” Schumer said in an interview on Tuesday of his talks with McConnell.

In theory once the trial starts, McConnell and his 53-member majority could ignore Schumer and establish rules on a partisan basis. Motions during the trial require a simple majority to pass. But a number of Republicans like Susan Collins of Maine want McConnell and Schumer to work out a deal rather than see the GOP majority steamroll Democrats.

“They’re still going to be working on it. That’s what we’re encouraging them to do,” said Sen. Lisa Murkowski (R-Alaska).

Marianne LeVine contributed to this report.