Fewer than three in 10 Americans think Sarah Palin's qualified to be president, according to a new national poll - the least of any of the five potential candidates included in the survey.But another woman tops that list in the CNN/Opinion Research Corporation survey released Monday: two-thirds of the public thinks that Secretary of State HIllary Clinton's qualified for the Oval Office. That's more than Vice President Joe Biden, who's currently next in line for the presidency.According to the poll, 28 percent of Americans say Palin is qualified to run the White House, with seven in 10 saying the former Alaska governor and 2008 Republican vice presidential nominee is not qualified.