On Fox News Sunday, Rick Perry sought to reassure GOP primary voters concerned about his wobbly presidential debate performances, saying he would draw sharp distinctions with the Democratic incumbent in televised showdowns next year.

The Texas governor, driving for front-runner status as the most viable conservative in the wide-open field, offered up samples of the scathing rhetoric he uses against the president, from the economy to war policy and personal credibility.

Perry also defended his voluntary flat-tax proposal and the notion that it could bring in trillions of dollars less in revenue than the current tax code.