What's making Romney hesitant to disclose taxes?

Mitt Romney says he'll release his 2011 tax return in April. This, after persistent calls for the Republican presidential hopeful to do so, particularly from fellow candidate Newt Gingrich.

But during last night's GOP debate, Romney "had a difficult time talking comfortably about his taxes," National Journal Congressional Correspondent Major Garrett observed on "CBS This Morning" Friday. It was, he noted, the second debate in a row where that happened.

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"I've been trying to figure out what the deal is in South Carolina is on this issue. He knows it's coming, he knows his father, when he ran for president in 1968, set a new standard of transparency, 12 years. It seemed that Mitt Romney didn't even know that story," Garrett said. "And when asked if he would meet that, he said 'maybe.' Why the level of discomfort? I can't quite figure it out."

But, Garrett suggested, a possible answer is that Romney is "uncomfortable releasing the charitable contributions he may have made to his church. The Mormon Church is an issue that doesn't cut well for him in South Carolina.

"He may be concerned about 10 or 20 percent of his income going to the church and that becoming a sudden issue in South Carolina. That's the only rational explanation I can come up with," Garrett said.

For more of Garrett's thoughts on the state of the Republican race, click on the video above.