Trump impeachment trial live updates: Biden says charge 'not in dispute' in 1st comments on acquittal

As Trump was tracking the impeachment trial from Mar-a-Lago, his Florida resort, he was not pleased with the performance of his defense team and specifically Bruce Castor, sources familiar with the matter told ABC News. 

Anticipating Trump’s eventual reaction, people close to the former president tried to keep his focus elsewhere, sources said, but he was watching portions of it. 

Trump had been bracing for a defense much less successful than his defense team during his first impeachment trial, but at times he was stunned to hear some of the arguments, specifically how Castor complimented the presentation by the Democrats, sources said.

-ABC News' Katherine Faulders and John Santucci 

Following the first full day of the Senate's first impeachment trial of a former president, Senate Majority Leader Chuck Schumer praised the performance of lead House impeachment manager Rep. Jamie Raskin, D-Md.

"I thought that manager Raskin’s argument was one of the most powerful I’ve ever seen. He hit it out of the park. It was both erudite and touching. It really -- it really got to your heart," Schumer said.

The trial resumes on Wednesday at noon with House managers making their opening arguments on the charge of "incitement of insurrection."

Sen. Bill Cassidy, R-La., told reporters on Capitol Hill Tuesday night that he voted that the trial was constitutional because of the "compelling argument" by the House managers.

"I always said, I would be an impartial juror, anyone that listened to those arguments would recognize that the House managers are focused, organized -- they relied both upon precedent, the Constitution and legal scholars," Cassidy said. "They made a compelling argument. President Trump’s team was disorganized, they did everything they could but to talk about the question at hand."

However, Cassidy stressed that he still is not sure how he will vote for conviction of the former president, repeating that he is an "impartial juror."

-ABC News' Trish Turner

The overwhelming majority of Republicans -- 44 senators -- voted against proceeding with Trump's impeachment trial, but one Republican unexpectedly sided with Democrats.

Sen. Bill Cassidy of Louisiana joined Sens. Mitt Romney of Utah, Lisa Murkowski or Alaska, Susan Collins of Maine, Pat Toomey of Pennsylvania, Ben Sasse of Nebraska who voted against dismissing the trial altogether last month.

"The fact that you have six Republicans now willing to go forward is telling, but of course, six is still a far cry from the 17 that they will need," said ABC News Senior White House Correspondent Mary Bruce, referring to the number needed to impeach Trump. "Even those Republicans who have condemned strongly the president's actions, who have said he bears responsibility that he provoked the mob that marched on the Capitol, still have argued that they do not feel that this is constitutional and that gives Republicans, some political cover in many ways.

"It will be interesting to hear from Sen. Cassidy certainly why he changed his mind or if that gives Democrats any hope that they may be able to change some other minds in the coming days," she said.

Asked earlier in the day if the House managers' presentation impacted him, Cassidy told reporters, "I’m trying to digest facts, and I thought the arguments they gave were strong arguments. Clearly, we have to hear the opposition, but they presented very good arguments" on the constitutional question, he said.