In a sign of their importance, Senate Republicans gave the opening question on Wednesday to Sens. Susan Collins of Maine, Lisa Murkowski of Alaska and Mitt Romney of Utah, three Republicans who hinted they could vote to hear from witnesses. But everybody's talking about the lawmaker who stayed quiet, Lamar Alexander of Tennessee.

“You cannot be acquitted if you don’t have a trial. You don’t have a trial if you don’t have witnesses and documentation and all of that,” Pelosi says.

President Donald Trump hasn’t been acquitted in the Senate trial yet, but Democratic leaders are already testing out their post-impeachment spin.

"He will not be acquitted," Speaker Nancy Pelosi declared to reporters during her weekly press conference on Thursday.

“You cannot be acquitted if you don’t have a trial. You don’t have a trial if you don’t have witnesses and documentation and all of that,” Pelosi (D-Calif.) added. “Does the president know right from wrong? I don't think so."

Senate Minority Leader Chuck Schumer (D-N.Y.) delivered a similar refrain at his press conference across the Capitol on Thursday.

A trial “without the evidence, without witnesses and documents would render the president’s acquittal meaningless,” Schumer said as the Senate prepares to begin what could be its second-to-last day of proceedings.

The Senate’s vote to acquit Trump on charges of abuse of power and obstruction of Congress, he argued, would have a “giant asterisk next to it, because the trial was so rigged in his favor.”

The argument — that Trump cannot be truly exonerated without a fair trial in the Senate — is clearly an attempt to undermine the White House’s victory lap after the president is acquitted, possibly as soon as Friday.

Schumer has been warning for weeks about the consequences of Republicans voting to acquit Trump through a "sham trial" without additional witnesses. But the closer the Senate gets to that possibility, the more Democrats have adopted that message and the sharper it gets.

While Democrats are still fighting to call more witnesses -- an argument a small number of Republicans are open to -- it’s widely expected by both sides that Trump will be acquitted given that 67 senators would have to vote to convict the president.

The forceful comments by Pelosi and Schumer on Thursday represent a clearer, sharper version of what Democrats have been arguing all week.

“Any conclusion that doesn’t allow witnesses and documents is going to make the president’s acquittal — if it should happen — worth very, very little. Zero,” Schumer told a swarm of reporters on Wednesday after the Senate’s first day of its question-and-answer session.

“You can’t convince the American people it was an acquittal if you don’t have witnesses and documents,” he said.

Democrats are already seizing on what they see as an attempt by Republicans to speed through a trial — that includes the increasing likelihood that a vote for acquittal could happen in the dead of night Friday after senators vote on whether to call additional witnesses.

For weeks, Democrats have been demanding Senate Majority Leader Mitch McConnell agree to allow additional witnesses and documents in the trial. The Democrats’ push gained new life earlier this week after claims surfaced from former national security adviser John Bolton that Trump told him he would continue withholding almost $400 million in aid until Ukraine helped investigate the president’s Democratic rivals.

The former national security adviser’s claims, detailed in an unpublished manuscript reported by the New York Times, rocked the Capitol on Monday as Republicans struggled to respond to questions about why Bolton shouldn’t testify.

The news also intensified pressure on the handful of moderate Republicans, including Sen. Susan Collins of Maine, who are being closely watched as they debate whether to side with Democrats and support a proposal to allow more witnesses to be called.

But the likelihood of Bolton or other witnesses being summoned to the Capitol appeared to fade over the next four days. By Thursday, GOP leaders signaled confidence they could defeat Democratic procedural motions on witnesses and other evidence.

Asked Thursday morning if he feels confident about the witness vote, McConnell told reporters: “I always do.”

Some of the most closely-watched moderate Republicans — Collins and Lisa Murkowski of Alaska — appeared Wednesday dissatisfied, at times, by the answers to their questions on the floor.

“We have people who are very comfortable with their positions, they think they've heard enough and are ready to move forward with a vote,” said Senate Majority Whip John Thune (R-S.D.).

“But we've still got some folks who are, like I said, assessing it and I think until this process is complete -- the question and answer sessions are through -- are probably going to keep their powder dry and that's fine."

Senators will begin another eight-hour round of questioning at 1 p.m. on Thursday.

Meanwhile, Schumer and other top Democrats have stepped up their attacks on White House lawyers for withholding key facts and refusing to fully answer questions about Trump’s conduct and motivations — another aspect of the trial they argue has been unfair to Democrats.

Schumer pointed to one question, in particular, when the White House counsel was asked to name one witness or one document to which House managers have been allowed access.

“And Mr. Philbin filibustered because he had no answer,” Schumer said, referring to deputy White House counsel Patrick Philbin.

Marianne LeVine and John Bresnahan contributed to this story.

U.S. Secretary of State Mike Pompeo faced a delicate balancing act as he began a two-day visit to Ukraine on Thursday, trying to boost U.S. ties with a critical ally that is at the heart of the impeachment trial while not providing fodder for Democrats seeking to oust President Donald Trump. Pompeo's visit comes as the Senate prepares to vote on whether to hear witnesses who could shed further light on Trump's actions toward Ukraine. Pompeo is the highest-ranking U.S. official to visit the country and meet with President Volodymyr Zelenskiy since the impeachment process began last year with revelations about a July 25 phone call between Trump and the Ukrainian leader.

Refocusing a debate on war and peace in the midst of the Senate impeachment trial, the Democratic-controlled House on Thursday approved measures reasserting congressional authority over war powers. In separate votes, the House passed a proposal to repeal the 2002 congressional authorization for the war in Iraq as well as a plan to prevent tax dollars from being used to take military action against Iran without congressional approval. Repeal of the 2002 authorization was approved by a 236-166 vote, while the funding measure on Iran passed 228-175.

Speaker Nancy Pelosi (D-Calif.) on Thursday hammered the lawyers leading President Trump's impeachment defense, saying they've trampled on the Constitution while questioning how they've been allowed to keep their licenses."I don't know how they can...

The Senate has eight more hours to ask whatever they want of House impeachment managers and Trump's defense team.