Obama's campaign announced 16 events where supporters planned to focus on "McCain losing track of how many homes he owns."
Tim Kaine, the Democratic governor of Virginia and a much-mentioned vice presidential prospect, took an early lead in mocking McCain.
"He couldn't count high enough, apparently, to know how many houses he owns," Kaine told CNN's "American Morning."
For Democrats, the kerfuffle carried a clear whiff of payback. Four years ago, Republicans turned a harsh spotlight on the five homes owned by the Democratic nominee, Massachusetts Sen. John F. Kerry, and his heiress wife, Teresa Heinz Kerry.
For Republicans, it was deja vu of another kind. Last month, one of McCain's top economic advisors, former Texas Sen. Phil Gramm, was forced to resign from the campaign after he told a newspaper that the United States was "a nation of whiners" who were suffering a "mental recession" over the economy.
By midafternoon, both campaigns were in full battle cry and sought to portray the other candidate as living an ostentatious lifestyle. Both campaigns called reporters, rushed out scathing TV attack ads, unveiled new websites and unleashed surrogates.
McCain, who huddled with advisors at his desert compound in Sedona, Ariz., said nothing in public. A nine-car motorcade took him to a nearby Starbucks early in the morning, where he ordered a large cappuccino. McCain otherwise avoided reporters.
Forced into damage-control mode, his campaign aides counterattacked to reinforce their claim that Obama is an elitist.
"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?" McCain spokesman Brian Rogers said in a statement. "Does a guy who worries about the price of arugula and thinks regular people 'cling' to guns and religion in the face of economic hardship really want to have a debate about who's in touch with regular Americans?"
Most of Obama's income stems from his two bestselling books and an advance on a children's book. He and his family stayed at a friend's home last week in Hawaii, where beaches, in fact, are all public. Obama spent part of his childhood in Hawaii, and his grandmother lives there.
