| By Laura Smith-Spark BBC News, Washington |
With only 75 days to go before elections to choose each party's presidential candidate begin, America's religious conservatives face an intractable dilemma.
Do they back the candidate they trust to promote the social values they hold dear - or the one who stands the best chance of beating the Democrats to the White House in 2008?
The Republican candidate currently leading national polls is former New York City Mayor Rudolph Giuliani.
But his support for gay and abortion rights, not to mention his three marriages, make him an unpalatable option for many social conservatives who would usually vote Republican.
"Giuliani still hasn't convinced folks that he is tolerable," said Richard Land, president of the Southern Baptist Convention's Ethics and Religious Liberty Commission and author of The Divided States of America.
"Once a social conservative becomes competitive in the polls, or comes within striking distance of being competitive in the polls, you are going to see Republican primary voters dropping off Rudy Giuliani like fleas off a dead dog."
'Unsettled' voters
The former New York mayor will doubtless try to change that view when he speaks at this weekend's Values Voter Summit that has brought all the Republican contenders to Washington.
A war is raging for the soul of America 
Family Research Council
Organised by the Family Research Council (FRC), a conservative organisation promoting Judeo-Christian values and the family, its aim is to galvanise social issues voters.
"A war is raging for the soul of America," FRC president Tony Perkins said. "What you or I do today will determine the future for generations yet to be born."
In the last two presidential elections, the evangelical Christian vote, motivated by issues such as abortion, gay marriage and embryonic stem cell research, was widely credited with helping George W Bush to victory.
Some 37% of all Republican and Republican-leaning voters are evangelical Protestants, the non-partisan Pew Research Center has found, and 43% say social issues will be "very important'' in deciding their vote in 2008.
But unless religious conservatives find a successor to Mr Bush behind whom they can unite, their power to influence this White House race remains uncertain.
Mr Land, one of the summit's speakers, told the BBC he saw conservatives as "unsettled and trying to make up their minds; listening to lots of marriage proposals and trying to decide which one to accept".
Wooing the right
Former Tennessee senator and actor Fred Thompson, criticised for lacklustre campaigning since announcing his candidacy in September, may have made some ground with Friday's wooing.
Entering the stage accompanied by second wife Jeri and three-year-old daughter Hayden, he cited his "100% pro-life voting record" in the Senate.
He also recounted how his opposition to abortion had become "of the heart" after seeing a sonogram of Hayden in the womb.
Mr Thompson went on to say he did not know what he would do in his first 100 days in office.
"But," he said, "I know what I would do the first hour: go into the Oval Office, close the door, and pray for the wisdom to do what was right."
The audience loved it, giving their loudest cheer of the morning.
Meanwhile, Arizona Senator John McCain also stressed his opposition to abortion and urged voters to trust him on conservative values. "I hope you know I'm not going to con you," he said.
'Electability'
Mr Thompson's performance was enough to win the backing of Brian Pikkaart, an IT worker from Virginia, who voted for the former Law & Order actor in the summit's straw poll.
"There's still a long time to go in the primaries, so things can change," he said.
"But at this point, it's a combination of knowing [Mr Thompson's] faith, his conservative beliefs across a spectrum of issues, and what I feel is his electability."
First-time Oklahoma voter Elise Hall, an intern with TeenPact, a non-profit Christian group working with teenagers, also praised Mr Thompson's family values.
Pastor Eric Yarbough, from Maryland, said he had felt a connection with Mr Thompson and Colorado congressman Tom Tancredo, but wanted to hear the other candidates before deciding his allegiance.
Recent retiree Norman Elser, from Ohio, agreed: "A setting like this, where they are all here, gives you a time to hear the different ideas and make your judgements and see how you want the election to go.
"I've narrowed it down to one or two but I haven't made my final decision yet."
'Not bluffing'
Ultimately, the religious right may have to choose between principle and pragmatism.
Last month a group of influential conservatives, including the founder of Focus on the Family, James Dobson, warned they would be forced to back a third-party candidate if Mr Giuliani won the Republican nomination.
Mr Land is convinced that the evangelical leadership will live up to that threat - even if it means splitting the Republican vote and losing the White House to, say, Democratic front-runner Hillary Clinton.
"Evangelicals have made it clear that they are not going to allow the Republican party to take for granted and exploit evangelicals the way the Democratic party has far too often exploited and taken for granted the African-Americans," he said.
"They are not bluffing."
However, Jean Schmidt, Republican representative for Ohio, urged voters to unite even "if it means having a candidate that we are a little bit uncomfortable with but who is less likely to compromise the values we hold...
"When we get through the primaries, stand behind the individual who is at least the better alternative than we will get from the other side."
