Mr Negron was handed what appeared to be an impossible political challenge last month when he was selected to replace Mark Foley, who resigned in disgrace on September 29 over lurid e-mails sent to male pageboys, as the Republican candidate for Florida’s 16th congressional district.

As the country recoiled in disgust at Mr Foley’s behaviour, and Republicans in dismay at yet another pre-election scandal, what had been a safe Republican seat suddenly looked a sure loss for the party in the House of Representatives — and yet another unexpected gain for the Democrats.

Under state law, Mr Foley’s name must remain on the ballot. Overnight, polls suddenly put the Democrat candidate, Tim Mahoney, into a 15-point lead. Few believed that Mr Negron could overcome the Foley scandal, and such disadvantages, in just five weeks.

But in the past 72 hours, after campaigning 18 hours a day across this sprawling south Florida district, the infusion of $2 million (£1.05m) by the national Republican party and a last-minute advertising blitz, Mr Negron has turned the race from a sure loser into a possible win. He has pulled almost even with Mr Mahoney.

The possibility of holding a seat that only a week ago was being viewed as another Democrat gain reflects the eleventh-hour strategy that Republicans are adopting in the last three days of campaigning: minimising the party losses in the House and holding the Senate.

Democrats need a net gain of 15 seats to take control of the House, and Republican strategists have privately conceded ten. Most pollsters predict that the Democrats will gain at least 20 seats, and perhaps more than 35. But with one full day of campaigning left, Republicans are focusing on 20 races — including the one featuring Mr Negron — where their superior get-out-the-vote operation and funding could pull enough struggling incumbents to victory.

Last night this final Republican blitz, including the message that Democrats are an unacceptable alternative, appeared to be having some success. In the crucial Montana Senate race, Conrad Burns, the Republican candidate, after trailing his Democrat opponent for months, had last night pulled even. A Republican win in Montana would dash Democrat hopes of gaining the six seats they need to retake the upper chamber.

In a Washington Post-ABC News poll, the Democrats’ generic advantage — 14 points last week — had dropped to six. Independents still favoured Democrats by 18 points, but that support had dropped from 28 points a fortnight ago.

In Florida, Mr Negron has been helped by a court ruling last week that allowed his campaign to print posters declaring that a vote for Foley on the ballot is a vote for Negron. The decision has spawned one of the best signs of the campaign: “Punch Foley for Joe”.

At a Veterans’ Day parade on Saturday, Mr Negron was busy shaking hands and reinforcing his relentless message: a vote for Mark Foley is actually a vote for Joe Negron.

“I got to say, having Mark Foley’s name is a real worry,” one woman, a Republican, told Mr Negron.

“I think people are figuring it out,” Mr Negron replied. Surveys indicate that nearly all voters realise that he is the candidate, and that the fallout of the scandal is dissipating.

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