Richard Painter, the chief White House ethics lawyer under President George W. Bush, tore into Senate Majority Leader Mitch McConnell over his plans for the Senate impeachment trial of President Trump.

"The oath of loyalty is to the United States of America, not to Donald Trump. These senators, Democrats and Republicans, have an obligation to hear the facts, to hear witnesses, and make a decision," Painter said Thursday on CNN's Anderson Cooper 360. "And for Mitch McConnell to say he’s working with the White House, coordinating with the defendant in this trial before the trial has even begun, is atrocious. He may think he’s a judge impaneling an all-white jury for a Klansman trial in Mississippi in 1965. That’s not the kind of trial we have."

[ Byron York: No, the Senate is not a jury, and other misconceptions about impeachment]

Former Pennsylvania Sen. Rick Santorum, who was also on the CNN panel, called Painter's comments "absurd." "I saw what Tom Daschle did in 1998, and I don’t think you were complaining one bit about him carrying the water for the president. This is typical, and I think completely appropriate," the former presidential candidate said.

Painter's comments come as Democrats are attempting to get McConnell to allow witnesses for the Senate trial. House Speaker Nancy Pelosi has threatened to withhold articles of impeachment if Senate Republicans did not hold a "fair trial."

