President Obama’s campaign ratcheted up its assault on Mitt Romney’s record as governor of Massachusetts on Monday, putting $10 million behind a tough new commercial that claims Mr. Romney had “one of the worst economic records in the country.” The advertisement will be broadcast in nine battleground states.

THE SCRIPT The ad opens with the words “September 2002” and an announcer’s voice: “It started like this.” Mr. Romney is shown at a debate where he says: “I speak the language of business. I know how jobs are created.”

The announcer narrates over images that suggest economic ruin: a vacant, dust-covered factory floor, an empty office, a pair of discarded work gloves. “But it ended like this: One of the worst economic records in the country. When Mitt Romney was governor, Massachusetts lost 40,000 manufacturing jobs — a rate twice the national average — and fell to 47th in job creation, fourth from the bottom. Instead of hiring workers from his own state, Romney outsourced call-center jobs to India.”

The next image on screen: a photo of Mr. Romney boarding a jet. “He cut taxes for millionaires like himself while raising them on the middle class and left the state $2.6 billion deeper in debt. So now, when Mitt Romney talks about what he’d do as president, remember, we’ve heard it all before.”