Last fall,taped an appearance on Kenneth Copeland's popular television show. The theme: "Integrity of Character."
"Treat people like you'd want to be treated," Huckabee said.
Now some are raising issue with Huckabee's character, principally his judgment, CBS News chief investigative correspondent Armen Keteyian reports.
They are focusing on his association with the televangelist, who has refused to cooperate with a Senate investigation into his ministry's finances.
At issue,CBS News last week: whether millions of dollars in tax-exempt church donations have been used to bankroll a lavish lifestyle and a slew of private, for-profit businesses.
"Mr. Huckabee has terrible judgment because not only is he being closely associated with someone under this ethical cloud, but he's refusing to distance himself," said Melanie Sloan, executive director of Citizens for Responsibility and Ethics In Washington.
When Huckabee appeared on Copleland's show, the evangelist said "Gov. Huckabee is not here in any kind of political role."
After his appearance, like many guests, Huckabee stayed overnight at the ministry's lavish 18,000 square foot lakefront home.
"All I know is he's a delightful human being," Huckabee said of Copeland.
But, before the show aired, Grassley's probe went public. So Copeland went back to the ex-Arkansas governor with an offering.
"I said, 'Governor, if this will negatively impact your campaign in any way, I won't run it,'" Copeland said. "He hollered at me on the phone and said, 'Are you kidding me?'"
CBS News has learned that Copeland's family has donated more than $29,000 to Huckabee's campaign.
And just three weeks ago - when Huckabee was on the financial ropes - Copeland helped raise thousands more from hundreds of ministers attending a meeting at his West Texas headquarters. Nobody is saying how much.
"If it's legal, legitimate, honest contributions, I'm not sure what the premise would be for giving that money back," Huckabee said.
For some, it may well be the premise of a presidential candidate not practicing what he preaches.