In scathing comments Thursday as her party appeared on the verge of defeat in the Senate impeachment trial, House Speaker Nancy Pelosi argued that President Trump "cannot be acquitted" if the trial lacks the witness testimony and documentation that Democrats have been seeking.

The San Francisco Democrat also fired on Trump's impeachment defense team, saying they've "disgraced themselves" during this week's trial and suggesting they deserve disbarment over their trial remarks.

The comments came hours before Sen. Lamar Alexander, R-Tenn., said he would not back efforts by Democrats to have witnesses testify at the Senate trial – all but sealing an acquittal for Trump.

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But Pelosi challenged whether that acquittal would be valid, in remarks that seemed a bid to undermine any Trump claim of victory.

"He will not be acquitted," Pelosi insisted during her weekly news conference, according to Politico. “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. Does the president know right from wrong? I don't think so.”

"He will not be acquitted. 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. Does the president know right from wrong? I don't think so.” — House Speaker Nancy Pelosi

Democrats have been seeking to have former national security adviser John Bolton, and possibly others, testify at the trial. Bolton, who was fired in September, is reportedly willing to provide testimony that could bolster the Democrats’ arguments that Trump abused his power by seeking a quid-pro-quo deal with Ukraine.

Meanwhile, Pelosi’s comments about Trump’s legal team were equally combative.

"I don't know how they can retain their lawyer status, in the comments that they're making," Pelosi told reporters, according to The Hill. "I don't think they made the case. I think they disgraced themselves terribly in terms of their violation of what our Constitution is about and what a president's behavior should be."

"I don't know how they can retain their lawyer status, in the comments that they're making. I don't think they made the case. I think they disgraced themselves terribly in terms of their violation of what our Constitution is about and what a president's behavior should be." — House Speaker Nancy Pelosi

Pelosi also accused other Trump allies of attempting “to dismantle the Constitution” in order to shield the president from conviction and removal from office over two articles of impeachment that the Democrat-controlled House approved in December.

“Some of them are even lawyers,” Pelosi said. “Imagine that you would say — ever, of any president, no matter who he or she is or whatever party -- if the president thinks that his or her presidency ... is good for the country, then any action is justified — including encouraging a foreign government to have an impact on our elections."

“[That] is exactly what our Founders were opposed to — and they feared,” she added, according to The Hill. “I don't think they made the case. I think they disgraced themselves terribly in terms of their violation of what our Constitution is about and what a president's behavior should be.”

Pelosi’s comments about the legal team were largely a reaction to Wednesday’s assertion by Trump attorney Alan Dershowitz, that, “If a president does something which he believes will help him get elected in the public interest, that cannot be the kind of quid pro quo that results in impeachment.”

Much of the media was quick to attack Dershowitz’s argument, comparing it to former President Richard Nixon’s 1977 comment to British interviewer David Frost that all presidential actions, particularly on national security, were legally justified.

"Well, when the president does it, that means that it is not illegal,” Nixon said.

Dershowitz pushed back on the criticism Thursday.

“I did not say or imply that a candidate could do anything to reassure his reelection,” Dershowitz wrote on Twitter, “only that seeking help in an election is not necessarily corrupt, citing the Lincoln and Obama examples. Critics have an obligation to respond to what I said, not to create straw men to attack.”

Dershowitz elaborated further during an appearance on Fox News’ “Hannity.”

"The point I was making was about the senators," Dershowitz said on "Hannity." "What I said [was] if you have mixed motives if you are in the public interest and you're trying to help the public, but you're also trying to get re-elected, according to [Rep. Adam] Schiff and [Rep. Jerry] Nadler, that's a crime.

Pelosi has faced her own share of criticism for stalling the impeachment process for about a month – by withholding the approved articles of impeachment from the Senate, seeking leverage in setting the parameters of the Senate trial -- after initially calling for “urgency” while House panels were holding their impeachment inquiries.

President Trump and other Republicans argued that Pelosi slowed down the process at least in part because she viewed the Democrats’ chances of winning a conviction of Trump in the Senate to be weak.

“We know their case is not strong and now they want to change the rules,” House Minority Leader Kevin McCarthy, R-Calif., said during an appearance on “Fox & Friends” in early January, referring to Senate Democrats’ call for witnesses at the trial.

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Late Thursday, the Democrats’ hopes of seeing Trump convicted took a severe blow when Alexander – one of a small group of Republicans thought to be sympathetic to approving witness testimony at the Senate trial – announced he opposed the effort.

Alexander’s decision made it unlikely that Democrats would attract enough Republican votes to win the argument for witnesses at the trial, making Trump’s acquittal all but certain.