At this point, Obama is the clear winner in the ad wars. Among swing-state voters who say the ads have changed their minds about a candidate, rather than just confirmed what they already thought, 76% now support the president, vs. 16% favoring Romney.

“We gave them new information,” says Obama campaign manager Jim Messina. “Romney had been out there claiming success as governor,” but Democratic ads have prompted voters to “take a look at his record” on job creation and as head of the private-equity firm Bain Capital. Messina also credits a $25 million buy for a positive ad “about the challenges the president inherited and what we had to do to move this country forward.”

To be sure, Obama’s ads have done more to win back Democrats than to win over independents or Republicans: Thirteen percent of Democrats say their minds have been changed by ads, compared with 9% of independents and 3% of Republicans…

In the 12 battleground states, the race is all but tied. Obama leads Romney 47%-45% among 1,200 registered voters in the poll June 22-29 — a tick closer than Obama’s 48%-44% lead among 2,404 voters in the rest of the USA over the same period.