Friday will be a crucial day in the impeachment trial of President Donald Trump.
The trial in the Republican-majority U.S. Senate could end Friday with Trump’s expected acquittal on charges of abuse of power and obstruction of Congress.
Or four Republicans could join 47 Democrats and independents in voting to allow witnesses to testify, including former National Security Adviser John Bolton, extending the trial for at least another week and maybe longer.
WATCH: Witness Vote Looms Over Trump Impeachment Trial
But if the vote to hear witnesses ends in a 50-50 tie, Supreme Court Chief Justice John Roberts, the presiding judge, could cast a deciding vote. But that would be unprecedented in an impeachment trial, so no one is sure what will happen.
The lead House impeachment manager, Democrat Adam Schiff, proposed hearing witnesses behind closed doors for no more than a week, saying that would let senators return to regular business.
Republicans have indicated they do not want any witnesses subpoenaed, believing that would drag out the trial and that more evidence could hurt their case.
Will Senate call witnesses?
Senate Majority Leader Mitch McConnell conceded earlier this week that he may not have the votes to prevent witnesses from being called. Several moderate Republicans have said they may be interested in hearing what Bolton has to say.
One of them, Sen. Susan Collins of Maine, said Thursday evening she would vote to allow witnesses. But Sen. Lamar Alexander of Tennessee, in a statement released shortly after Collins’ announcement, that there was “no need for more evidence.”
In a yet-to-be-published book, Bolton said Trump told him he was withholding $391 million in military aid to Ukraine until President Volodymyr Zelenskiy publicly announced an investigation of former Vice President Joe Biden, a potential political rival of Trump’s in the 2020 presidential election.
Democrats said reaching out to a foreign power to interfere in an election is an impeachable offense.
Trump’s lawyers say the president had the right to hold up the aid over concern for corruption in Ukraine and a demand that Europe do more to help Ukraine fight Russian-backed separatists.
Trump’s defense team and the impeachment managers Thursday spent their second day answering questions from the senators, which were read by Roberts.
Roberts refused to ask a question handed in by Kentucky Republican Rand Paul because it reportedly would have identified the whistleblower, whose concern about Trump’s July phone call in which he asked Zelenskiy for a favor led to the president’s impeachment. Paul denied the question would have outed the whistleblower.
Trump’s attorneys continued to argue that nothing the president did concerning Ukraine is impeachable.
White House counsel Pat Cipollone said Democrats are trying to get rid of a president they don’t like, saying it is up to voters to decide whom they want.
When Patrick Philbin, a Trump attorney, said the president’s personal lawyer, Rudy Giuliani, was only “a source of information” and not carrying out foreign policy in Ukraine, Schiff called that statement “breathtaking.”
Schiff said the attorneys blew up their whole case by seeming to admit that Giuliani was in Ukraine on a personal political errand for Trump.
Witnesses during the impeachment hearing testified that Giuliani was in Ukraine to pressure officials to investigate Biden for corruption even when no evidence against the former vice president ever surfaced.