The Senate affirmed the constitutional basis of former U.S. President Donald Trump’s second impeachment trial, clearing the way for arguments to begin on whether he incited an insurrection by inflaming the mob that stormed the U.S. Capitol last month.

After four hours of arguments from House of Representatives impeachment managers and Trump’s defense team, the Senate voted 56-44 to proceed with the trial, rejecting the former president’s contention that it is unconstitutional to try an official who is no longer in office.

Six Republicans joined with Democrats in voting to continue to the trial: Lisa Murkowski of Alaska, Bill Cassidy of Louisiana, Susan Collins of Maine, Mitt Romney of Utah, Ben Sasse of Nebraska and Pat Toomey of Pennsylvania. Still, that is far short of the 67 votes that would be required for a conviction. Opening arguments are set to begin at noon on Wednesday.