Obama ad pits Romney against middle class

The ad, titled "Heavy Load," says the "middle class is carrying a heavy load" but that Mitt Romney "doesn't see it."

"Under the Romney plan, a middle class family will pay an average of up to $2,000 more a year in taxes, while at the same time giving multimillionaires like himself a $250,000 tax cut," a narrator says over images of Mitt Romney and a large home.

"Romney hits the middle class harder and gives millionaires an even bigger break," the ad concludes.

"The president's vision for the middle class and where this country is going to be moving forward" is the focus of the Democratic convention Obama campaign spokesperson Adam Fetcher told CBSNews.com.

The Romney campaign, meanwhile, is expected hit back this week by asking voters if they are better off than they were four years ago.

"Mitt Romney's plan will lower rates across the board, helping create jobs and higher take-home pay. Americans are asking a simple question: are we better off than four years ago?" Romney spokesperson Amanda Henneberg wrote in an email. "With the Romney-Ryan plan for a stronger middle class, the next four years will be better than the last four."