The Obama campaign ad attacking Mitt Romney's record at Bain Capital was a shameless exaggeration but a brilliant political pivot. Instead of running on his record-where he is vulnerable to Mr. Romney-the president is making character the issue.

President Obama promised a lot when he ran for president-to fix the trade deficits with China and on oil, which together steal some five million jobs, curb the excesses at Wall Street banks, and curb escalating health care costs.

In perfectly choreographed fashion, the Bain ad characterized Mr. Romney as someone who bought up healthy businesses, loaded them with debt and then drove into bankruptcy-destroying jobs to enrich his private equity partners. 

Cory Booker, the Democratic mayor of Newark, made headlines calling the ad "nauseating to the American public," and that gave Mr. Obama the perfect opportunity to attack Mr. Romney, oh so effectively.