Barack Obama has a new radio ad running in the Potomac Primary region, stressing both his pitch for change and a focus on economic issues, where Hillary Clinton has often been able to out-finesse him according to many exit polls — and the Hillary camp has been quick to respond.

"Barack Obama understands the strains we're facing," the narrator says, later adding that Obama has, "An economic plan that jump-starts the economy, with tax cuts for middle class families and seniors. A health plan that lowers costs by $2500 for a typical family and provides universal coverage."

The Hillary camp's rebuttal: "Top independent health care experts have concluded that Sen. Obama's plan is not universal and would leave at least 15 million people without coverage. Leaving so many people out will drive up costs for everyone."