Economist Stephen Moore, a longtime ally of Donald Trump who advised his 2016 presidential campaign, said on Thursday that the siege of the Capitol by Trump supporters less than 24 hours prior marked a "terrible day for America," acknowledging that Trump "should have conceded long ago.”

When asked if Trump bears responsibility for the attack, Moore said, “I do not know.” But he criticized Trump’s conduct in the months since his election defeat last November. “He should’ve said ‘I’m not going to contest this,’” Moore says.

The critical remarks from a top ally of Trump came amid a slew of resignations from his administration and calls for his removal through the invocation of the 25th Amendment, as the U.S. reckons with an attack on the Capitol that led to the evacuation of elected officials from both chambers and four deaths.

Most notably, Transportation Secretary Elaine Chao stepped down from her position on Thursday, and Illinois Representative Adam Kinzinger became the first Republican member of Congress to back the removal of Trump via the 25th Amendment.

Moore asserted baseless claims of widespread voter fraud, but said he was “disgusted” by the attack on the Capitol and concerned that the mayhem may “destroy Trump’s policy legacy.”

‘Arrested, cuffed, and interrogated’

The economist is not the only Trump ally to have harsh words about the mob that entered the Capitol on Wednesday. Billionaire grocery magnate John Catsimatidis and Arkansas businessman Warren Stephens — both top political donors to Trump — also condemned the siege of the Capitol in comments made to Yahoo Finance.

“The people that broke into the building should all be arrested, cuffed, and interrogated,” Catsimatidis says.

But he said that he doesn’t think Trump “bears any blame,” faulting instead the rioters who disrupted Congress and the police who failed to prevent their entry into the Capitol.

Stephens, who gave $1 million to a pro-Trump Super Pac last January, likewise denounced the attack.

“I unequivocally condemn the rioters that breached the Capitol and those who encouraged them,” Stephens said in a statement. “We cannot tolerate any threat to undermine American democracy and our electoral process. Those who participated should be fully prosecuted.”

Through a spokesperson, Intercontinental Exchange CEO Jeffrey Sprecher — who donated $1 million to a pro-Trump Super Pac last April — also condemned the storming of the Capitol.

“Mr. Sprecher joins with leaders in the business community in condemning the lawlessness that transpired at the Capitol yesterday,” the spokesperson said.