The emergence of Sarah Palin as a political force in the presidential race has left many top Democrats fretting that, just two weeks after their convention ended on a emotional high, Barack Obama's campaign has suddenly lost its stride.
Obama has responded aggressively this week to Palin's presence on the Republican ticket, using television ads and campaign rallies to attack her contention that she is a political reformer who will take on the Washington establishment -- a role Obama has long claimed as his alone.
But some Democrats are now worried about the perils of Obama's strategy, saying that his campaign, instead of engaging the Alaska governor, should avoid any move that draws more attention to her and could enhance her appeal among the white, blue-collar voters who remain cool to Obama's candidacy.
A series of new polls suggest that Palin has given a major boost to John McCain's campaign, exciting the GOP base, winning over white women and erasing Obama's lead. Concern among Democrats was high enough Tuesday that Sen. Richard Durbin, D-Ill., one of Obama's strongest supporters, felt it necessary to cite historic polling data at a lunch of Democratic senators to convince them that post-convention "bounces," such as the one that has followed last week's GOP convention, have often faded in past elections.
To reassure nervous lawmakers, Durbin also reviewed Democratic registration gains this year in key battleground states.
Still, Democrats expressed anxiety about the new challenge suggested by the recent surveys showing McCain has gained ground among independent voters and women, who could decide the race in states such as Ohio, Michigan, Pennsylvania and Virginia.
A new Wall Street Journal/NBC News poll released Tuesday, for instance, shows that McCain is now winning white women 52 percent to 41 percent after having been virtually tied with Obama in that crucial category just a month ago.
"Whenever you see that kind of movement, you ought to be concerned; you ought to try to address it," said Rep. Elijah Cummings, D-Md., a strong Obama backer.
David Bonior, the former Michigan congressman who managed Democrat John Edwards unsuccessful presidential bid, called the new poll findings a "real concern," adding: "We can't lose white women and expect to do well in this race."
One Democratic operative familiar with the campaign's deliberations worried that the "freshness, newness and aura around Barack has been eclipsed. The campaign has been knocked offstride."
Another explained that Democrats expected Palin to "have the opposite effect" and drag McCain down, and added, "Whenever there is conventional wisdom in Washington, and it's wrong, that shakes people up."
The two Democrats, like others interviewed for this story, requested anonymity in order to speak about internal campaign strategy.
Obama over the last two days has begun vigorously attacking Palin for decisions she made as governor and has tried to tarnish her image as a political maverick and reformer, highlighting, for example, her initial support for the "bridge to nowhere."
One new TV ad released this week accuses Palin of "lying" in claiming to have killed the $398 million link between Ketchikan and its island airport. McCain has ridiculed the project as an egregious example of the kind of pork-barrel spending he has long fought.
Palin has made her opposition to the federally funded bridge a staple of her stump speech, even though she defended it in her 2006 campaign and did not kill it until it was clear that Congress would not pay for it.
Also, Obama and his aides have started using increasingly aggressive language in recent days to denounce Palin's and McCain's attempts to cast themselves as the harbingers of change.
The typically even-keeled Obama on Tuesday night invoked an old cliche and accused Republicans of trying to put "lipstick on a pig" in their adoption of the change mantra, noting that not long ago McCain had tried to present himself as the candidate of experience.
Republicans seized on the comment and tried to portray it as a sexist allusion to Palin, who in her convention speech said that the only difference between a hockey mom and a bulldog was lipstick.
Obama aides waved off the attacks as a "pathetic attempt to play the gender card."
It was not clear late Tuesday whether the lipstick spat would garner much attention, but the exchange demonstrated the challenges facing Obama as the McCain camp tries to squeeze every advantage possible out of the Palin candidacy.
Some Democrats are eager for Obama to be even harder on Palin.
Rep. Chris Van Hollen, D-Md., chairman of the Democratic Congressional Campaign Committee, said that the enthusiasm of independent voters for Palin will fade when her conservative record is better known. "They need to get that information out and they need to get it out quickly," he said.
But others say Obama will only help the GOP by attacking Palin, and he should try to relegate her to the margins of the campaign, where his own running mate, Joe Biden, now seems to be residing.
Moreover, some said, attacking a charismatic woman too harshly can backfire. They worried that it would play directly into the Republican strategy of courting female voters and portraying Palin as a middle-class mom under fire from the left and the establishment media. At the same time, they fear it could cloud Obama's carefully honed image as a post-partisan politician.
"The Obama campaign should stick to their message and not overreact to Palin," said one Democratic strategist. The strategist added that accusing Palin of being a liar is "a long way from their core brand and shows that they haven't found the answer of how to deal with her."
Democratic consultant Eric Jaye, who works with candidates in Michigan, a working-class state that Republicans feel is now more in play because of Palin, said the Obama campaign needs to be "very careful not to turn Sarah Palin into a working-class heroine."
Obama aides have said this week that the campaign's position remains strong in key battleground states, and that its formidable get-out-the-vote operation will carry it to victory despite the Palin buzz.
Campaign manager David Plouffe dismissed Palin's potency so far, saying she had been relying on scripted speeches and was doing little more than energizing the GOP's core conservative base.
"The question is: over time, day after day, week after week in these last eight weeks, you know, how does that take hold with the swing voters, and what does that really mean to their field operation?" Plouffe said. "And you know, do they have the architecture and the infrastructure to really take advantage of it?"
- Times staff writers Dan Morain and Noam N. Levey contributed to this report.