Barack Obama holds a slight advantage over John McCain going into the final phase of the 2008 presidential campaign, which is shaping up more as a personality contest than a battle of ideas.

WASHINGTON — Barack Obama holds a slight advantage over John McCain going into the final phase of the 2008 presidential campaign, which is shaping up more as a personality contest than a battle of ideas.

Both candidates are framing the choice for voters around a theme of change, but strategists — foreshadowing continued attacks by both campaigns and a heavy dose of negative ads — say that McCain's chances for winning ultimately might depend on his ability to stoke doubts about Obama's readiness for the presidency.

"There are more Democrats than Republicans in America today, and Obama would still be the favorite to win. But I would not be surprised if McCain upset him," said Merle Black, an Emory University political scientist.

Because Obama "is somebody who's really unknown in any great detail to most Americans," the presidential debates, which begin the week after next, might be unusually important in helping undecided voters make up their mind, he added.

"The McCain campaign understands that its candidate has a better chance of winning a contest over character than over issues," William Galston of the liberal Brookings Institution wrote in a post-convention analysis. McCain is presenting himself as "a safe choice for uncertain times."

"Obama's challenge," he added, "is to make Americans comfortable with the idea of him as president so that the forces underlying this year's contest come to the fore. ... It is a testament to McCain's personal appeal — and to the uncertainty Obama has not yet dispelled — that the race remains as close as it is."

Paul Wilson, a Republican media consultant and occasional adviser to the McCain camp, said the election "is getting framed as this massive personality battle. You would think it would be about the economy, and you would think the war would be in there some place, but so far they're not."

Obama strategists say that McCain's pick of Alaska Gov. Sarah Palin as his running mate was part of an effort to set up an argument over social values and such hot-button topics as gay marriage and abortion. But they predicted that any attempt to revive the culture wars of past campaigns would be overwhelmed by economic worries in most voters' minds.

Republicans hope that Palin, a religious conservative with strong anti-abortion views, will help McCain attract more votes from the women and socially conservative Catholics he needs to defeat Obama.

Palin's initial effect on the election was described as "a wash" by Gary Langer of ABC News, in an analysis of a national opinion survey about McCain's vice presidential pick. Reactions to Palin broke heavily along the existing partisan divide, the poll found, and produced no immediate boost for McCain among women voters. Moderate independents, an important target for both campaigns, reacted more positively to Joe Biden, the Democratic vice presidential nominee, than to Palin, according to the survey.

Palin's emergence as a new Republican star has energized the religious and social conservatives who play important roles as campaign volunteers and might have remained on the sidelines. Mike DuHaime, the McCain campaign political director, said the number of volunteers had quadrupled last weekend, after Palin's selection was announced.

But Robert Gibbs, a senior Obama aide, said that "the jury is still out on how (Palin) plays in, say, a lot of suburban counties throughout the country, where, we think, swing voters will decide the election."

Strategists in both parties have expressed nervousness about the election, and most predicted that the outcome would remain in doubt until the campaign's final days.

For months, Obama has been underperforming in the polls, which show that voters are more unhappy with the way things are going in the country than in any recent presidential year and that more want a Democrat than a Republican in the White House. When voters are asked which party they identify with, they pick the Democrats by a wide margin, and President Bush's unpopularity has been a drag on Republican candidates nationwide.

Party strategists and independent surveys indicate that Obama continues to be dogged by doubts about the extent of his government experience, resistance from traditional Democrats and independents because of his race, and cultural differences between white working-class voters and the liberal Democratic nominee.

At the same time, Republicans are worried about McCain's inability to grab the lead. According to Gallup, about 1 in 5 registered voters is still up for grabs.

Record TV audiences — McCain's convention speech slightly outdrew Obama's — reflect unusually high levels of voter interest in this year's campaign and suggest that turnout could be up significantly Nov. 4.

Polls show that voters are eager to see the country move in a different direction. But critics say that neither Obama nor McCain has laid out an all-embracing agenda or provided a coherent explanation of the organizing principles for his presidency beyond sometimes vague calls for reform and sets of positions that largely conform to the existing doctrines of their parties.

Some Democrats privately fault Obama for not laying out a foundation for his candidacy the way Bill Clinton did in 1992, when he ran as a new Democrat on a program of ideas designed to move his party back to the center. One veteran of the Clinton White House said Obama has never made it clear that he has "real ideas for solving the country's challenges."

For now, the Democrat is emphasizing pocketbook issues such as energy, gas prices, health care, jobs and college tuition. McCain is highlighting the need for more U.S. drilling for oil and gas, along with cutting spending and keeping taxes low.

In a departure for Republican candidates in recent elections, McCain has de-emphasized issues of terrorism and homeland security. Bush made the fight against Islamic terrorism a centerpiece of his successful 2004 re-election, but that issue didn't help Republicans enough in 2006, when change-minded voters gave control of Congress back to the Democrats.

"Surprisingly enough, some of the foreign policy issues have not been as dominant in the general election as they were in the primary battles," said Gibbs, the Obama adviser. But he predicted that developments in Iraq and Afghanistan would play into voter decisions this fall and noted that Obama is linking the cost of the war to Washington's failure to make needed investments at home.

Obama's campaign has invested heavily in trying to expand the electoral playing field, putting organizers and TV ad money into traditionally Republican states from North Dakota to Georgia. The McCain campaign has been slow to respond. For example, there are no paid McCain workers in North Dakota, according to DuHaime.

DuHaime said the McCain campaign was in the process of "adding infrastructure," opening more offices and hiring campaign workers. McCain is concentrating his efforts on about 15 states, including many of those the Obama campaign is targeting.

The election is likely to be decided on many of the same battlefields of the last two presidential contests, assuming that the race remains close. Almost 40 of the 50 states already tilt toward one party or another.

So that handful of tossup states were among the first to see the candidates as they left their conventions. Obama headed for Democratic-leaning Pennsylvania and Michigan, which McCain is trying hard to peel away. McCain took off for Democratic-leaning Wisconsin, then campaigned in Colorado and New Mexico, '04 Republican states with large Hispanic populations that Obama has put in play.