Republican presidential candidate Sam Brownback said rival Mike Huckabee should apologize for a supporter's "prejudiced whisper campaign" against him for being Catholic.

According to a report by The Associated Press, Rev. Tim Rude, pastor of Walnut Creek Community Church, sent an e-mail to Brownback supporters pointing out that Huckabee is an evangelical Protestant and Brownback is not. In the e-mail, Rude calls Huckabee — a former Arkansas governor and an ordained Baptist minister — "one of us."

"I know Senator Brownback converted to Roman Catholicism in 2002," wrote Rude. "Frankly, as a recovering Catholic myself, that is all I need to know about his discernment when compared to the governor's."

Rude apologized Tuesday, saying he never meant to sound critical of Catholicism.

"In no way do I think a Catholic would not make a great president,” he reportedly said. “In fact, if Governor Huckabee drops out of the race, I will support Senator Brownback."

Brownback said through a spokesman that Huckabee should apologize. But Huckabee's campaign did not. Huckabee spokesman Eric Woolson said Rude is not a campaign staffer and was expressing a personal opinion in a private e-mail.