WASHINGTON, DC -- As the U.S. Senate trial of President Donald Trump resumed Thursday, lead House impeachment manager Rep. Adam Schiff of California argued the law and the Constitution, applied to the facts, support article one of impeachment that accuses him of "abuse of power."
After laying out the timeline of Trump's pressure campaign against the Ukraine, including withholding military aid to get Ukraine to announce an investigation of former Vice President Joe Biden and his son, Hunter, Schiff argued that the president violated the Constitution.
Schiff had the room’s full attention, but some senators appeared restless as the arguments continued in the Thursday afternoon session. Republican Sen. Lindsay Graham of South Carolina complimented Schiff on the presentation of the House case, but asked "will it stand up?"
Another House impeachment manager, Rep. Jerry Nadler of New York, contended that Trump "puts President Nixon to shame" in abusing power.
As of Thursday, Democrats had roughly 16 hours left to use over two days before the president's legal team takes the Senate floor on Saturday to begin their 24 hours of opening arguments over three days.
The Trump legal team is concerned their Saturday arguments will get buried and may request a time change. A GOP source told ABC News that eliminating the Saturday session was also a possibility.
Alan Dershowitz, the former Harvard Law professor who is playing a role on Trump's defense team, is expected to argue, as he's been doing on TV, that a sitting president cannot be impeached for "abuse of power" as Democrats charge.
During the first of three days of opening arguments on Wednesday, Democrats flatly dismissed the notion of offering Joe or Hunter Biden as witnesses in exchange for Trump's former National Security Adviser John Bolton, Senate Minority Leader Chuck Schumer told reporters, "That trade is not on the table."
At a Thursday morning news conference, without saying their names, Schumer called again on four Republican senators -- Lisa Murkowski of Alaska, Susan Collins of Maine, Mitt Romey of Utah and Lamar Alexander of Tennessee -- to join Democrats in calling for witnesses and documents, before directly addressing the president and his GOP allies.
Schumer said a Trump acquittal in the Senate trial would have "zero value" if no witnesses are called to testify.
"I will say this to president and any of my Republican friends: if the American people believe this is not a fair trial, which right now they seem to believe because there were no witnesses and documents, acquittal will have zero value to the president or to the Republicans," he said.
Asked about reports of possible deal on witnesses, Schumer said not a single Republican has approached him on the subject -- further shutting down the idea.
"No Republicans are talking to us about deals. We want four witnesses ... they go to the truth," he said.
"The bottom line is the president is clearly covering up, his people are covering up, and the question is: Will our Republican colleagues rise to their constitutional mandate to create a fair trial," Schumer added rhetorically, "and I don't think it will sit very well with history or with the American people if they don't."