WASHINGTON -- Gov. Rick Perry sought Sunday to reassure Republican primary voters concerned about his wobbly presidential debate performances, saying he would draw sharp distinctions with the Democratic incumbent in televised showdowns next year."I'm not worried a bit that I'll be able to stand on the stage with Barack Obama and draw a very bright line," Perry said.Driving for front-runner status as the most viable conservative in a wide-open field, he 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."There's nothing wrong with lower revenue," he said. "I don't want more revenue in Washington, D.C.'s hands. I want more revenue in the private sector job creators' hands."Perry is managing the fallout from his debate performances as all of the GOP candidates fight to lead the pack in Iowa just two months before the first voting of 2012 begins there.No clear leader has emerged in that contest. A Des Moines Register poll Saturday showed former Godfather's Pizza CEO Herman Cain at the head of the pack, with the support of 23 percent of respondents. Former Massachusetts Gov. Mitt Romney was next with 22 percent.Perry, who rated just 7 percent in that survey, has taken a particularly steep fall since announcing his candidacy in August, struggling through parts of five debates and dogged especially by Romney.How, he was asked on Fox News Sunday, would he perform against Obama next year?What counts, Perry said, is how a candidate would govern. "We got a great debater, a smooth politician in the White House right now, that's not working really good for America," Perry said.Perry plans to attend four of the debates now scheduled in November as well as one in December. "With as many debates as we got coming up, I may end up being a pretty good debater before it's all been said and done," he said.On Iraq and Afghanistan, Perry accused Obama of pursuing an "aimless foreign policy" by making big decisions without adequately considering the advice of his commanders. He said the president has endangered Americans on the ground by announcing that U.S. troops will leave Iraq by year's end."He has lost his standing from the standpoint of being a commander in chief who has any idea about what's going on in those theaters," Perry said.On the leading domestic issue, Perry said the president has "taken an experiment with the American economy and turned it into an absolute Frankenstein experience."Cain piled on the president, too. "A responsible commander in chief" would have done more to seek the counsel of the military's ground commanders before agreeing to pull all troops out of Iraq, Cain said on CBS' Face the Nation.