Many don't particularly like him. Some see an irascible loose cannon, others a political heretic. Conservatives still distrust him.

Yet Republicans in the United States now view him as the one man with a chance of rescuing the party from its worst electoral defeat in a generation: John McCain, their presidential-nominee elect, who has often quarrelled with his own colleagues.

Amid the blanket coverage this week of the battle between Barack Obama and Hillary Clinton, there was an election result in rural Mississippi that sent waves of panic through the Republican party. It forced an admission from its congressional leaders that public disgust with the Republican brand was now so great that they could suffer an electoral bloodbath not seen since the Watergate era.

The special election, the US equivalent of a by-election, was for a House of Representatives seat in Bible Belt Mississippi, a district President Bush carried by 62 per cent in 2004.

The Republican candidate, Greg Davis, tried to link his Democratic opponent, Travis Childers, to Barack Obama. The Vice-President, Dick Cheney, flew there to stump for him. The cash-strapped National Republican Campaign Committee (NRCC) sank $1.3 million into the race. Yet Mr Childers won by eight points, the third special election defeat for Republicans in “safe” congressional seats this year.

The Mississippi result triggered fears within the party that it could lose up to 25 seats in the House, and even face the prospect of a 60-seat Democratic majority in the Senate, the magic number that would allow a Democratic president to pass legislation almost unimpeded. Tom Davis, a Virginia congressman and former leader of the NRCC, said of the three losses: “They are canaries in the coal mine, warning of far greater losses [in November]. The political atmosphere facing House Republicans this November is the worst since Watergate.” In 1974, three months after President Nixon's resignation, Republicans lost 48 seats in the House and four in the Senate.

Eight in ten Americans now view the country as “on the wrong track”, a historic high, and Mr Bush's disapproval rating is the highest for a US president since such polling began.

In an effort to “rebrand” the party, Republican leaders offered a risible new slogan: “The Change You Deserve”. Not only did it appear plagiarised from Mr Obama's “Change We Can Believe In”, it was also the advertising slogan for the anti-depressant Effexor, whose side effects include sweating, nervousness and nausea.

Democrats seized control of both chambers of Congress in the 2006 mid-term elections. They hold a majority of 37 in the House and a one-seat advantage in the 100-member Senate. Although reaching 60 Senate seats will be difficult, Democrats think they have a good chance of taking up to seven Republican seats and increasing their House majority to perhaps 70.

So far, as the result in Mississippi suggested, attempts to damage Democratic candidates by linking them to Mr Obama have failed. Even producing the Republican trump card of national security has had mixed results. Mr Bush's attempt during a speech to the Knesset in Israel on Thursday to link the Democratic frontrunner to Nazi appeasers provoked a furious response from Democrats and dismay among many Republicans. Even Hillary Clinton defended her rival. In South Dakota yesterday, Mr Obama called it “an appalling attack that divides our country, and alienates us from the world.”

The one person, therefore, who could prevent a Democratic grand slam from one end of Pennsylvania Avenue to the other is Mr McCain. A White House victory for him would give him the power of the veto and the muscle to set his own legislative goals. His image as a more independent-minded maverick appears so far to have inoculated him against anti-Republican sentiment. The latest poll has him tied with Mr Obama.

Only four times since 1928 has the winning president's party lost seats on Capitol Hill. “I have no illusions about this,” Mr McCain said. “This campaign will be a very difficult challenge.”

Times Recommends

• Gloves off as McCain lands Obama 'lie' jibe
• Anger as terrorist gets bail for IVF
• US hands palace of Saddam back to Iraqis