McCain's Challenge Is Underscored by Pullout From Michigan.

    The faltering economy has left Sen. John McCain on the political defensive, altering the landscape in many of the most important battleground states and providing a series of avenues for Sen. Barack Obama to claim the 270 electoral votes needed to win the White House in November, according to political strategists in both parties.

    Over the past two weeks, Obama has opened up leads both nationally and in the states likely to decide the outcome of the presidential election. A combination of factors - the tumult in the financial and credit markets, the performance of the two candidates in responding to it, and increased doubts about Alaska Gov. Sarah Palin - have contributed.

    McCain's abrupt decision last week to take down his television ads in Michigan and to shift staff to other states highlighted the increasingly challenging environment in which the Republican nominee now finds himself.

    Michigan once was seen by the McCain campaign as a prime target for shifting a big industrial state to the Republican column in what would have been a major blow to Obama. But strategists said the economic downturn, which has hit Michigan especially hard, appeared to be too much for McCain to overcome.

    Now he is faced with defending a series of states that supported President Bush four years ago but are currently in danger of going for Obama. Prime among those is Florida. McCain's neglect of the state over the summer, coupled with the effects of the subprime mortgage crisis that has been acute in the Sunshine State, have turned must-win Florida, with 27 electoral votes, into a struggle for the Arizona senator.

    The GOP nominee also faces mounting challenges in other red states. Strategists see Iowa and New Mexico, both of which went narrowly for Bush four years ago, as leaning strongly toward Obama. Two other red states, Virginia and Colorado, now tilt slightly toward Obama. And McCain faces fights in states that once were considered virtually off-limits to Democrats, such as North Carolina and Indiana.

    Obama is playing defense in some blue states, as well, particularly Pennsylvania. A McCain breakthrough there would significantly complicate Obama's strategy, and the Democrat's advisers are guarded in their assessment of the situation there.

    Mike DuHaime, the McCain campaign's political director, said yesterday that the decision to pull out of Michigan does not leave the campaign in a totally defensive position. "Our path to victory is clear," he said. "There are a number of close [Republican] states we are confident we will hold and no shortage of Democrat-leaning states that I feel we have a very good chance of winning."

    Obama's team, meanwhile, sees the past two weeks as having kept it on a path charted earlier in the summer.

    "I think we've got many more variables, many more scenarios and possibilities than they do, and that's always been our goal - to wake up on November 4th with a series of scenarios that lead to 270 electoral votes," senior Obama strategist David Axelrod said. "We're on track to do that. I think their options are growing more limited."

    Obama needs those options. If McCain simply managed to replicate Bush's electoral map from four years ago, he would be president. Holding the states Sen. John F. Kerry won four years ago would give Obama 252 electoral votes.

    To get to 270, Obama could try the one-state option - going all-out to win a big state such as Florida or Ohio, which alone would put him over 270 if he also held the states Kerry won. Or Obama could try the two-state strategy, keyed to winning Virginia and a smaller state such as Iowa or New Mexico. There is also what Obama's advisers dub the three-state approach, coupling wins in Iowa and New Mexico with one in Colorado.

    GOP strategists outside the McCain campaign say the heavier burden is on the Republican nominee. "The big electoral map story is that they are caught playing defense in states they ought to be in good shape in," said Mike Murphy, a GOP consultant who previously worked for McCain. "They are having to fight to hold onto North Carolina, Virginia, quite possibly Florida, and their offensive campaign appears limited to Wisconsin, Minnesota and Pennsylvania."

    Obama also enjoys an advantage in money. Because he chose not to take public funds - after saying that he would pursue an agreement with the GOP nominee to do so - he can spend as much as he can raise. McCain is limited to the federal money and what the Republican National Committee can provide his campaign, and the Michigan decision was seen as an acknowledgment that he needs to concentrate his money where it counts most.

    McCain advisers insisted that their decision to leave Michigan does not reflect broader problems, and said that they are challenging Obama on numerous fronts. On a conference call with reporters, strategist Greg Strimple said that McCain is tied or ahead in enough states to deliver 260 electoral votes, just shy of putting him over the top.

    "We are currently competing aggressively in Minnesota, Iowa, Wisconsin, Colorado, Pennsylvania, Nevada, New Hampshire and New Mexico," Strimple said. "The combination of any of those states, we have to get 10 more electoral votes in order to be successful and have Mr. McCain as the next president of the United States."

    But Democrats - and public polls - show problems for McCain in Iowa, New Mexico and, increasingly, in Minnesota.

    Pennsylvania offers an especially enticing opportunity for McCain, with its 21 electoral votes and large swaths of white, working-class voters who favored Sen. Hillary Rodham Clinton in the Democratic primary contest.

    McCain and Palin have visited the state repeatedly, making an aggressive play for votes in the Democratically inclined suburbs of Philadelphia, where Obama did not do as well as expected in the primary, and in the more traditionally conservative areas farther west.

    Recent polls showed Obama forging a clear lead in the state, and Obama advisers think they will benefit from the surge in Democratic registration there this year. There are now about 1.1 million more Democrats registered in the state than Republicans.

    In the hope of continuing that trend before the new registration deadline on Monday, the Obama campaign enlisted Bruce Springsteen to give a free concert in Philadelphia this weekend so that volunteers could track down new, unregistered voters in time for them to be added to the rolls.

    Still, Obama advisers are wary about the state because of its older population, the relatively high percentage of Roman Catholic voters and what advisers see as racially based resistance to Obama's candidacy. "I don't think we can take that at all for granted," one Obama adviser said.

    The travel schedule his campaign has devised for the candidate, as well as his wife, Michelle, and running mate Sen. Joseph R. Biden Jr. - with frequent trips to Republican areas and states such as Virginia, where both Obama and Biden are this weekend - reflects a growing sense of confidence that Obama is on the right course since briefly stalling after the Republican convention.

    "We've had a good few weeks," Axelrod said in an interview on Friday. "The debates have gone well for us. Obama has handled the economic issues well. McCain, I think, has not. So I think we've made progress, and that's reflected in myriad public polls. But we expect a pitched battle from now to November 4th, and we're not intoxicated by these polls any more than we were depressed by negative polls when we've seen them before."

    Beyond Pennsylvania, McCain's blue-state targets include Wisconsin - one of the closest states in 2000 and 2004 - and New Hampshire.

    Kerry won New Hampshire in 2004. In the midterm elections two years later, voters wiped out the state's all-Republican congressional delegation to elect two Democrats to the U.S. House. But it is also an iconoclastic swing state with a deep current of affection for McCain - and the place where Obama suffered his first primary defeat to Clinton.

    "It's tighter than it should be in New Hampshire," said Doug Hattaway, a Boston-based Democratic consultant who worked for Clinton in the primaries and is advising Jeanne Shaheen in her efforts to unseat Sen. John E. Sununu (R) there.

    He said that, given Democratic growth over the past few years, Obama could expect to be in stronger shape, but added, "New Hampshire is sort of tailor-made for McCain, with its independent streak, and he is well-known and well-liked there."

    Another wild card for both candidates is the northern half of Maine, which splits its electoral college votes in half by congressional district. McCain is making a play for the 1st District, where the conservative, rural sensibility seems to be a natural fit for Palin.

    In acknowledging the decision to abandon Michigan, McCain advisers sought to portray it as a sensible move that would allow greater concentration on Maine, Missouri, Indiana and Pennsylvania, among others. Yet it was a stunning admission; campaigns often pretend to compete in states they have all but lost to try to confuse their opponents and hold onto an outside chance of winning toward the end.

    On Friday, Palin said she had read the news that her ticket had pulled out of Michigan and strongly disagreed. "I read that this morning and fired off a quick e-mail and said, 'Oh, come on, do we have to?' " Palin told Fox News, adding that she and her husband, Todd, would be able to appeal to workers in the distressed auto industry. "We can relate to them and connect to them... I want to get to Michigan, and I want to try."