"Your recent actions show that you flagrantly violated the Code of Conduct and I am urging you to resign from your position on the federal District Court of Montana effective immediately,” he wrote.

Cebull earlier in March apologized for what he called “very poor judgment on my part.” He admitted the email, which he forwarded to seven addresses from his official account, contained racist content.

"The only reason I can explain it to you is I am not a fan of our president, but this goes beyond not being a fan," Cebull said. "I didn't send it as racist, although that's what it is. I sent it out because it's anti-Obama."

Although Cebull apologized, several Democrats have indicated that is not enough.

“An apology alone is not acceptable," said Congressional Black Caucus Chairman Emanuel Cleaver (D-Mo.) earlier this month.

“There is no justification for using taxpayer resources to forward such a racist, inflammatory email,” wrote Johnson.

Reps. Steve Cohen (D-Tenn.) and John Conyers Jr. (D-Mich.) also sent a letter to the House Judiciary Committee on Tuesday asking that a hearing be called to examine the matter, according to a report by USA Today.

--This post was updated at 4:27 p.m.