Washington, D.C. ? Republican presidential hopeful Sam Brownback said rival Mike Huckabee should apologize for a supporter’s “prejudiced whisper campaign” against him for being Catholic.

The supporter, a pastor in Windsor Heights, Iowa, sent an e-mail to Brownback supporters pointing out that Huckabee is an evangelical Protestant and Brownback is not.

Huckabee, a former Arkansas governor, is an ordained Baptist minister.

“I know Senator Brownback converted to Roman Catholicism in 2002,” the Rev. Tim Rude, pastor of Walnut Creek Community Church, wrote in the e-mail. “Frankly, as a recovering Catholic myself, that is all I need to know about his discernment when compared to the governor’s.”

In the e-mail, Rude calls Huckabee “one of us.”

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

Brownback, a Methodist until he converted, said through a spokesman that Huckabee should apologize. With days to go before the Aug. 11 Iowa straw poll, a traditional measure of strength, Brownback’s campaign has sparred with several other campaigns.