|PIC1|Widening political divisions in the once-united US evangelical community as Arizona Senator John McCain closes in on the Republican presidential nomination could hurt the party in the November White House race.

Republican candidate Mitt Romney dropped out of the US presidential race on Thursday, a decision that almost certainly will make McCain the nominee of his party.

But that is an unappealing prospect to some conservative white evangelical Protestants, whose support could prove to be the difference in the November election against a galvanised Democratic Party.

McCain is an abortion-rights foe but his failure to support a constitutional amendment to ban gay marriage and backing of embryonic stem-cell research are among the political heresies that some conservative evangelicals cannot forgive him for.

With the influential James Dobson, the founder of the conservative advocacy group Focus on the Family, already saying he will not vote for McCain, analysts say evangelical turnout - or lack thereof - could be key on November 4.

"It's possible that the lack of enthusiasm for McCain could lead to a lower turnout among evangelicals in the fall," said Scott Keeter of the Pew Research Center.

That scenario could tilt the election in favour of the Democrats as Republicans have come to rely heavily on an evangelical community energised to get out and vote by its opposition to abortion rights and gay rights.

Their vote was widely seen as the difference for President George W Bush in his two successful White House runs.

"Anything short of a fully engaged and mobilised Republican base will spell disaster for the Republican nominee," said Tony Perkins, president of the Family Research Council, a conservative lobby group with strong evangelical ties.

"Evangelicals do more than vote ... they volunteer, they work in campaigns. They'll do volunteer phone work and pass out flyers," he said.

Evangelicals comprise about a fifth of the US population and according to Pew surveys account for at least a third of the Republican electorate, giving them serious clout in politics.

MCCAIN: THE AGONY AND THE ECSTASY

On the surface, the 71-year-old McCain would seem an ideal candidate in evangelical eyes.

He has long opposed abortion rights - the litmus test for many conservative Christians - and as a Vietnam veteran and former prisoner of war he is regarded as a national war hero.

His tough guy persona and unflinching support for the Iraq war also resonate with many evangelicals, who see the "war on terrorism" as part of a broader "clash of civilisations" and Middle East events as unfolding biblical prophecy.

And exit polls show he has been picking up as much as a third of the evangelical vote or more in some states.

But the Republican evangelical vote remains divided, largely because of the continued presence in the race of Mike Huckabee, a Baptist preacher and former Arkansas governor.

And some evangelicals will clearly not warm to McCain for the reasons Dobson and other conservative Christians have outlined, such as his support for embryonic stem cell research and campaign finance reform which many evangelicals believe hampers their ability to participate in the electoral process.

Still, some evangelicals are glad to back an anti-abortion candidate who they see as much more of a uniter for their movement than former New York Mayor Rudy Giuliani, a supporter of abortion rights who once led the polls but faltered and dropped out.

"I'm concerned with the disunity among Christian conservatives and I am upset with the pundits bashing McCain. I think he (McCain) is a very honourable man. I think we have to get united or else the Democrats will win," said Rix Tillman, a Southern Baptist pastor based in El Paso, Texas.

McCain also appeals to evangelicals who have conservative views in areas such as abortion but are more liberal on social and economic issues and thus he can be a bridge between the old "Religious Right" and the "evangelical centre".