CHESAPEAKE, Va. — Democrat Barack Obama on Thursday seized on a report that John McCain didn't know how many houses he and his wealthy wife own, launching a TV ad portraying his Republican opponent as out of touch, attacking him on the stump for it and dispatching surrogates in battleground states to do the same.
His strategy pleased many Democrats who've been urging him to go negative, but it also prompted McCain to renew his earlier criticisms of the Illinois senator as elitist and hypocritical.
The stepped-up attacks on McCain came as Obama prepared to name a running mate and accept his party's nomination for president next week at the Democratic National Convention in Denver.
Obama said Thursday, "I've made the selection" of a running mate, but he wouldn't name his choice or say whether he'd made the offer, had been accepted or when he might announce it.
The controversy over McCain's real estate holdings erupted after the Arizona senator told a reporter for Politico on Wednesday that he'd have his staff get back to him about how many homes he and wife, Cindy, have. She's the wealthy owner of a large beer distributorship in Phoenix that she inherited from her father.
McCain's staff initially said he had at least four homes. The Obama campaign, citing property records, found seven. Politico on Thursday reported finding a record for an eighth.
At an evening town hall meeting in Chesapeake, the crowd lapped up Obama's critique of McCain's houses. Obama said he wasn't simply trying to give McCain "a hard time" but that he thought that "it's indicative of a different worldview about what's happening in America."
"Obama, Obama," the audience chanted approvingly.
In Obama's 30-second TV ad, an announcer says, "Maybe you're just struggling to pay the mortgage on your home," and that when McCain was asked how many homes he owns, he "lost track" of the number. "Here's one house Americans can't afford to let John McCain move into," the announcer says, referring to the White House.
The ad aims simultaneously to anger Americans hit by the mortgage crisis, redefine voters' impression of McCain as a war hero and maverick politician, and turn the tables on the idea that Obama, a Harvard Law graduate, is the one who's elitist.
The description of McCain losing track of his homes, however, seemed to build on another attack that Obama supporters have been accused of making but have denied: that McCain, 71, is confused or forgetful.
McCain spokesman Brian Rogers shot back in a statement: "Does a guy who made more than $4 million last year, just got back from vacation on a private beach in Hawaii and bought his own million-dollar mansion with the help of a convicted felon really want to get into a debate about houses?"
Sales of Obama's best-selling memoir and a subsequent book have made him wealthy. Hawaii, where he vacationed, is where he was raised and where his grandmother and half-sister live. Rogers' last reference was to Antoin Rezko, a Chicago developer who'd supported Obama politically and whose wife sold property to the Obamas. Rezko was convicted this year of several counts of fraud and bribery, but Obama wasn't connected to the case.
Late Thursday, the McCain campaign released a TV ad titled "Housing Problem" that highlights Rezko's connection to the Obamas' purchase of a home.
The McCain spokesman also characterized Obama as "a guy who worries about the price of arugula and thinks regular people 'cling' to guns and religion in the face of economic hardship," referring to two of the Democrat's earlier campaign gaffes.
On the campaign trail, Obama told a town hall audience at a community college in Chester, near Richmond, "If you don't know how many houses you have, then it's not surprising you might think the economy is fundamentally strong."
Obama said he had only one home.
In Pennsylvania and Florida, the Obama campaign announced statewide searches for "anyone who doesn't know how many houses they own." In Montana, an event was planned at a house that's facing foreclosure. Democrats put together a Web site with a map and photos of the McCains' properties, including high-end beach and resort properties.
With Obama expected to announce his running mate soon, he was joined on the trail Thursday by one friend who's considered a contender for the job, Virginia Gov. Tim Kaine. Kaine wouldn't say whether Obama had tapped him for the job or had told him it would be someone else.
Speculation continued to swirl around other Democrats as well, including Indiana Sen. Evan Bayh and Delaware Sen. Joseph Biden, to a lesser degree Kansas Gov. Kathleen Sebelius and Obama's former rival for the nomination, New York Sen. Hillary Clinton, or whether a dark-horse candidate might emerge.
(William Douglas contributed to this article from Washington.)