Rudy Giuliani will address thousands of Christian conservatives tomorrow whose grip over the Republican party for the past generation is being steadily loosened by the success of his presidential attempt.

His eight rivals for the Republican nomination are also scheduled to speak at the Values Voters’ Summit in Washington this weekend but attention will inevitably focus on the former New York Mayor.

Despite being a supporter of gun control, abortion and gay rights, as well as a self-confessed adulterer who is on his third marriage, Mr Giuliani has stubbornly retained a substantial lead over the rest of the field.

His front-runner status has caused panic and division within the Religious Right, which has become used to exercising profound — if not decisive — influence over the Republicans’ choice of presidential candidates.

Mr Giuliani sidesteps much of the social policy that has defined the party in recent years, preferring to concentrate on his reputation as “America’s Mayor” after the 9/11 attacks.

Recent polls suggest that he does well among social and religious conservatives who regard the “war against Islamic terrorism”, and support for Israel in particular, as a moral issue. The other main themes of his campaign have been to highlight his fiscal conservatism and polling evidence showing that he is the Republican best able to beat Hillary Clinton.

A speech on Wednesday in Des Moines, Iowa, for instance, was mostly about Mammon, partly Hillary-bashing, but did not once mention God. He talked about cutting taxes, competition in healthcare and free trade. In answer to a question about making Iowa a “green state”, Mr Giuliani said that he associated the colour with dollar bills, known as greenbacks, and suggested that the best way to make a better environment was to “make lots of money” through cleaner technology.

Some conservatives believe that it is time to cut a deal with this wealth- creating social liberal who might save them from Mrs Clinton. Rick Parry, the Governor of Texas, told the Iowa audience that after “much prayer” he had decided to back Mr Giuliani because he had promised to appoint conservative Supreme Court judges.

But Richard Land, a leader of the Southern Baptist Convention, likes to point out that Mr Giuliani had “also promised two previous wives that he would love, honour and cherish them until death do us part”. A group of 50 evangelical leaders, led by James Dobson, of the Focus on the Family group, have pledged to vote for a “minor- party candidate” who opposes abortion if the New Yorker is nominated by Republicans.

Others have urged the movement to use this weekend to unite around one of Mr Giuliani’s rivals, but there is little sign of a consensus emerging over their preferred candidate. Many champion Fred Thompson, but support for him has waned after an admission that he does not attend church regularly and would be content for states to recognise gay marriage.

There are also strong reservations about socially conservative candidates such as Mitt Romney, whose Mormon faith is regarded as a sect by evangelicals, and John McCain, who described them as “agents of intolerance”.

Mike Huckabee, a former Arkansas governor who until recently has scarcely figured in the race, is suddenly attracting interest from the Christian Right. One poll this week in Iowa, a socially conservative state that kicks off the nominating process in January, put his support at 18 per cent.

Mr Giuliani languished in fourth place in that poll, but his campaign strategy is based on winning the more populous and socially liberal states holding ballots in February.

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