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An election campaign that has crackled with historic potential for almost two years against a backdrop of war and economic crisis is reaching its climax. Yesterday Barack Obama forged deep into enemy terrority in a final attempt to sway voters before tomorrow’s election and secure the 270 electoral college votes needed to win the White House.

Even John McCain, who has concentrated on campaigning in his Republican heartlands, ventured into Pennsylvania and New Hampshire yesterday — an acknowledgement that he must pick up some Democratic states to offset expected losses elsewhere.

Mr Obama, with a commanding lead in national opinion polls and across many of the battleground states that he must win to become the first black US President, spent the final hours of his campaign inside Republican territory, travelling over the weekend across three timezones. On Saturday he was in Nevada, Colorado and Missouri, yesterday he was in Ohio, today he will be in Florida, North Carolina and Virginia. All these states were won by President Bush four years ago. Mr Obama’s campaign team is confident of holding the 252 electoral college votes secured by John Kerry in 2004 and say that he will cross the finishing line if he captures just two or three of up to a dozen target states. He has even begun advertising in Arizona, John McCain’s home state, while eyeing the possibility of winning long-shot contests in Montana, Georgia and North Dakota.

Mr McCain is seeking an unlikely path to victory. He is hoping that polls have overestimated support for Mr Obama and that an anticipated surge in turnout among African-Americans and young people fails to materialise, or can be neutralised by a flood of conservative white votes from rural areas. Most of his campaigning over the past week has been in the traditional swing states of Ohio, Florida and Missouri, as well as once solidly Republican Virginia and North Carolina. Rick Davis, his campaign manager, said the Republicans — heavily outspent for most of this election — had splashed out $100 million on a final hours “get-out-the-vote operation” and would at last be able to match Mr Obama’s TV advertising spending.

He acknowledged that Mr McCain faced an “awfully difficult political climate”, but had “battled back” with polls tightening in states such as Pennsylvania over recent days. “He is going to show the American public what a real comeback is about.”

Republicans in Pennsylvania put out a TV commercial yesterday highlighting Mr Obama’s links to his former pastor, the Rev Jeremiah Wright, whose racially charged sermons threatened to derail the Democrat’s candidacy earlier this year.

Mr McCain has consistently refused to make an issue of this. Nationally, the party has begun bombarding supporters of Hillary Clinton with automated telephone calls repeating some of the attacks she made against Mr Obama in the Democratic primary.

Mr Obama, speaking in Columbus yesterday, warned supporters to expect “more of the slash and burn, say-anything, do-anything politics that’s calculated to divide and distract”. But he added: “I know this, Ohio, the time for change has come. We have a righteous wind at our back.”

His campaign was yesterday running adverts showing Dick Cheney endorsing the Republican on Saturday night. “And boy did McCain earn it,” says the voice-over. “He voted with Bush and Cheney 90 per cent of the time. That’s not the change we need.”

David Plouffe, Mr Obama’s campaign manager, said that evidence of registered Democrats outnumbering Republicans in early voting was providing a cushion against any late surge by Mr McCain in states such as Colorado, where almost half the electorate has already cast its ballots. “I think we have a decisive edge. John McCain will have to win by huge margins to make up these differences,” he said

With warm and dry weather forecast for tomorrow, a record turnout of at least 130 million people is expected.

Mr McCain meanwhile appeared on Saturday Night Live with Tina Fey — who has mercilessly caricatured his running-mate, Sarah Palin — to make light of his campaign’s modest means. He pretended he had been forced to a shopping channel “infomercial”, reminding tomorrow’s voters that “all undergarments are non-refundable”.

Fey, in her Palin role, turned to the camera: “Okay, listen up, everybody. I am goin’ rogue right now, so keep your voices down. Available now, we got a buncha these ‘Palin in 2012’ T-shirts. Just try and wait until after Tuesday to wear ‘em, okay?”

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