An adviser to President Barack Obama's re-election campaign says GOP presidential candidate Rick Santorum went "well over the line" when he questioned Obama's Christian values.

Robert Gibbs tells ABC's "This Week" that it's time "to get rid of this mindset in our politics that, if we disagree, we have to question character and faith."

Gibbs says the country would be better served if presidential candidates focused instead on the economic challenges faced by the middle class.

Santorum said on Saturday that Obama's agenda is tied to "some phony theology" not based on the Bible.

Gibbs' forceful rebuke suggests Obama's campaign is taking Santorum more seriously these days as a potential general election challenger.