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 privately 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 in national opinion surveys. Obama briefly touched 50 percent in the Gallup's national tracking poll last week, while McCain hasn't been able to break above the mid-40s since the primaries ended in June.
According to Gallup, about 1 in 5 registered voters is still up for grabs.
Record TV audiences - McCain's 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 on 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 liberal or conservative doctrines of their parties.
