New ads aim for candidates' weaknesses

In the president's ad called "Stretch," he said, "You work hard, stretch every penny, but chances are you pay a higher tax rate than him: Mitt Romney made $20 million in 2010, but only paid 14 percent in taxes - probably less than you." (Watch Obama's ad "Stretch" above.)

The ad continues: "Now he has a plan that will give millionaires another tax break and raises taxes on middle class families by up to $2,000 a year. Mitt Romney's middle class tax increase: he pays less, you pay more."

The ad, which is running in New Hampshire, Virginia, North Carolina, Florida, Ohio, Iowa, Colorado and Nevada is referencing a new report by the Tax Policy Center that says Romney's tax plan would raise taxes on middle income Americans and reduce taxes for the wealthiest Americans.

Obama leads Romney in three key swing states
Foreign trip behind him, Romney charges forward
Obama: Romney wants tax cuts for "people like him"

For his part, Romney is fighting back with his own ad, running in the battleground state of Florida. It speaks directly to a ongoing drain on the Sunshine State's economy, which has an unemployment rate above the national average at 8.6 percent, and a severely depressed housing market with one of the highest foreclosure rates in the nation. (Watch Romney's ad "Focus" below.)

"Under President Obama, 8.6 percent unemployment, record foreclosures, six hundred thousand ore Floridians in poverty. He focused on Obamacare instead of jobs. Barack Obama: what a disappointment," the narrator says.