In 2004, the "hot button" policies curtailing abortion and same-sex marriage were seen as being crucial to Republican electoral success in, for example, the key swing states of Ohio and Florida.

But in last November's Congressional races - where Democrats regained control of both the House and the Senate - some Republican defeats came at the hands of a new religiously-inspired movement, which some are calling the "evangelical left".

Switching allegiance?

The reality may be that the new movement is more centrist - and fed-up with being lumped in with the orthodox religious right leadership.

It is not so much that swathes of once Republican-supporting evangelicals are switching allegiance but more a question of taking a sceptical look at the narrow agenda that has defined their relationship with the Republican Party, according to John Green, of the Pew Forum on Religion and Public Life.

"Questions like climate change, poverty and international human rights are coming to the fore, in a community that didn't used to talk about these things at all," Mr Green said.

Evidence of a subtle realignment, can be seen in the main sanctuary of Northland Church, in Orlando, Florida - a space that used to be a roller-skating rink until it was taken over by Pastor Joel Hunter.

The conservatively-dressed but sprightly mid-Westerner serves a 7,000-strong congregation that broadcasts its services live to thousands more on the internet.

He recently wrote a book called "Right Wing, Wrong Bird" outlining his concerns, and hopes for the future.

"There has to emerge a new constituency and a new set of leaders for the evangelical Christians in this country," he told the BBC Heart and Soul programme.

Power struggle

"We want to build a culture of life - but that includes the vulnerable outside the womb, as well as the vulnerable inside the womb.

"We've had too long a time where we make people who disagree with us into enemies," he added.

"I think that's not Christ-like or even intelligent. This whole thing is not a struggle over ideology, it's a struggle over power."

The call to broaden the agenda as the campaign for the White House intensifies is looked on with dismay just a few miles from Northland Church by activists who still back the fundamentalist strategies of the religious right.

John Stemberger is an attorney and president of the Florida Family Planning Council, who respects Joel Hunter's conservative credentials, but not his argument.

"The institutions of marriage and the family are under attack," he said.

"The problem with the religious left is that they are helping the party that we believe is going to reverse the flow.

"None of us think the Republicans are saints ... but you have to pick a party in order to play the game, and be successful in enacting policy in our country."

The politicians most affected by fissures among conservative religious voters, are the Republican presidential candidates vying for their support.

Mike Huckabee is a former governor of Arkansas and a Baptist minister.

Despite his religious credentials, he is trailing far behind the current front-runner, former New York Mayor Rudy Giuliani.

It is a sign of the complex new relationship between the religious right and the Republicans that Mr Giuliani, who is dubbed "America's Mayor", is doing all he can to avoid talking about his own Catholicism, mindful perhaps that thrice-married candidates can hardly be strong on personal morality issues.

'Blowing bridges up'

Mr Huckabee is disillusioned by the behaviour of the religious right leadership.

He said: "I think in many cases, they've become intoxicated with a taste of power.

"They like it - they're now looking at 'well, who's going to win, because we want to make sure that we're attached to the inevitable winner,'" he told the BBC.

He thinks the religious right could be throwing away its positive influence.

"If they don't have something about which they are uniquely united ... they really serve no particular purpose," he said.

But back in Florida, the evidence on the ground is that voters who identify strongly with the religious right cannot be taken for granted and will not be told what to think anymore.

Sitting with a glass of iced-tea in the spacious home of Gary Whitlock - whose family all worship at Northland Church - he talked about how he had worked tirelessly to get out the vote for George W Bush.

Old certainties have changed and he is not certain that he will be voting Republican in 2008.

He said: "I'm not so sure the political affiliation of the person that's elected is important, so much as what the person who's elected believes.

"What the political process needs to have more of is bridge-builders, rather than people who are blowing bridges up and trying to create chasms between us."