Story highlights Sen. Al Franken's replacement Tina Smith is in Washington on Monday

Sen. Al Franken said December 6 he would resign "in the coming weeks"

Washington (CNN) Democratic Sen. Pat Leahy expressed regret Monday for not waiting for an ethics investigation before calling for Sen. Al Franken to resign, coming just hours after Sen. Joe Manchin made similar comments about the Democratic push for the Minnesota senator to step down.

"I have stood for due process throughout my years as a prosecutor and in chairing the Judiciary Committee. I regret not doing that this time. The Ethics Committee should have been allowed to investigate and make its recommendation," Leahy said in a statement.

On December 6, Leahy joined a wide number of other Democrats in urging Franken to step aside after another woman came forward with allegations of an unwanted sexual advance from before he was senator.

"I am concerned that even a prompt Ethics Committee investigation and recommendations will not come soon enough," Leahy said at the time. "He has to step aside."

Politico first reported Monday morning that Leahy privately told Franken of his regret.

Read More