They have been sprouting across the front lawns of western Pennsylvania, just enough of them among the Hallowe’en ghouls and zombie decorations to give John McCain the ghost of a chance.

The signs read, “Another Democrat for McCain”. They are to be found at the homes of women like Eileen Kettelberg, a factory worker who has been a Democrat all her life but will not vote for Barack Obama because she believes he insulted Hillary Clinton – and, by extension, all Democratic women – by failing to pick her as his running mate.

There is another one outside Joyce Wiczorek’s home in Franklin. “I just don’t feel I know who Obama is,” the 57-year-old former teacher said last week. “With McCain and Sarah Palin, at least you know who you’re getting.”

There are other reasons why blue-collar Pennsylvania Democrats are considering a Republican vote this year. Some cite Obama’s liberal views on abortion and perceived antipathy to gun-owners. Others think that McCain, a Vietnam veteran, cares more about their sons and daughters who are serving in Iraq. Many are worried by McCain’s claims that Obama is a closet socialist who is planning to “punish the successful”.

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Both Democratic and Republican officials suspect that at least some of these reasons are camouflage for racism. “There are still some people who have trouble voting for a person who is part African-American,” said Tom Balya, commissioner of Pennsylvania’s Westmoreland County, which is expected to vote for McCain even though 50,000 more Democrats are registered as voters there than Republicans.

All these factors help to explain why the state that first rejected Obama when it voted overwhelmingly for Clinton in the Democratic primary earlier this year has become McCain’s last best hope of confounding the polls and pulling off the mother of all presidential upsets. A win in Pennsylvania might offset Republican losses in smaller states elsewhere.

“It’s wonderful to fool the pundits because we’re going to win the state of Pennsylvania,” McCain told a rally in Hershey last week. That he could make that claim without sounding hopelessly deluded – he is up to 12 points behind in local polls – was a measure of both the late burst of optimism that the 72-year-old Arizona senator has managed to inject into his dishevelled campaign and the unsettling social tensions that have scarred the contest in one of America’s most divided communities.

By any orthodox calculation, McCain should be slinking home to Phoenix on Tuesday while his party tears itself to pieces over an ugly, shambolic campaign riven by internal feuding. Burdened with the legacy of eight years of Republican mismanagement under President George W Bush, McCain struggled to provide a coherent alternative; lost his main political advantage when the economy overtook the war in Iraq as the main concern to voters; and never seemed sure whether his running mate, Sarah Palin, was a breath of fresh air or a pain in his neck.

Yet somehow he is still in with a chance, albeit one that even his closest aides admit is slim. “He is facing a major struggle to win,” acknowledged Arnold Schwarzenegger, the Republican governor of California, who joined McCain in Ohio on Friday. “But I have seen him in those major struggles in the past when he has come back when everyone counted him out.”

On the banks of the Stonycreek River in Johnstown, home to one of Pennsylvania’s biggest steel plants, it is not hard to understand why both McCain and Palin have spent so much time wooing disaffected Democrats in this out-of-the-way valley.

When Palin visited Johnstown last month, some of the locals who flocked to her meeting carried stuffed monkeys with pictures of Obama pinned to their faces. There were shouts of “Get back to Africa” and “Obama Osama”.

Jack Murtha, the town’s veteran Democratic congressman, stirred a national controversy when he declared: “This is a racist area.” Having been reelected 17 times, Murtha is suddenly facing a spirited Republican challenge led by William Russell, a retired US army colonel.

The effect of all this has been to blur traditional political loyalties and to present McCain with an ugly but exploitable opportunity. If he manages to hang on to historically Republican states such as Florida, Ohio, Virginia and North Carolina, he can turn the tables on Obama by stealing the Democratic vote in Pennsylvania.

How likely is that? Bill McInturff, his chief pollster, claimed in a strategy memo last week that undecided voters – at least 8% of the total – were swinging towards McCain. His campaign also claims success among so-called “Wal-Mart women” – wives and mothers with no college degree who shop at America’s largest superstore.

The biggest question mark remains Palin, who at varying stages of the campaign has been dismissed by disgruntled McCain aides as a “diva” and a “whack job” who has “gone rogue”. The voters will decide. As Palin declared last week: “I truly believe that the wisdom of the people will be revealed on [polling] day.”

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