Sen. Rand Paul (R-Ky.) on Thursday said hearing that Supreme Court Chief Justice John Roberts would not preside over former President Trump's upcoming impeachment trial "crystalized" the GOP argument that the proceedings are unconstitutional.

Paul emerged as a hero for Trump supporters this week after he used a little-known procedural tactic, a privileged constitutional point of order, to strike a severe blow to Democrats' hopes of convicting the former president on a House-passed article of impeachment.

Forty-five Republican senators voted this week to support Paul's motion that said Trump's impeachment trial is unconstitutional since he's no longer in office. //

Paul said the news that Senate President Pro Tempore Patrick Leahy (D-Vt.) would preside over the second impeachment trial struck many Republicans as deeply unfair. Leahy voted to convict Trump on two articles of impeachment last year.

"The optics of the chief justice not coming and then also the optics of a person who had favored the last impeachment now presiding over the trial - who's also going to vote in the trial - it just didn't look right or sound right to any of us," he added.