Appearing separately before about 1,000 conservative activists, the Republican candidates all pledged to protect the unborn, defend traditional marriage, limit government and bring an end to the presidency of Democrat Barack Obama.
But Cain, the former pizza executive, came under indirect fire for seeming to suggest earlier this week that while he opposed abortion, government should not be trying to tell a woman what to do about it.
"It is a liberal canard to say I am personally pro-life, but government should stay out of that decision," Texas Governor Rick Perry told the Iowa forum, held in an exhibition hall at the Iowa State Fairgrounds.
"If that is your view, you are not pro-life," he said, without mentioning Cain by name. "You are pro having your cake and eating it too."
Bachmann also criticized Cain's abortion comments without naming him, saying she believed government must intervene to protect the unborn and she would support a constitutional amendment on the issue.
Bachmann, a representative from Minnesota, also said she would never consider negotiating the release of detainees at Guantanamo Bay -- a direct rebuttal of Cain's recent comment that he would consider trading them for a U.S. hostage.
Cain, who has struggled in the past week as his views come under more scrutiny, has tried to backtrack on both of those comments. At the forum he was direct when asked about his stance on abortion. "No abortions, no exceptions," he said.
The forum was heavy on social issues, and all of the candidates were asked by the forum sponsors what they would do to end abortion on demand. Former Senator Rick Santorum questioned the commitment of the other candidates to fight on the issue.
The conservative activists at the forum, sponsored by the Faith and Freedom Coalition, gave all of the candidates similar polite but not wildly enthusiastic responses.
'A BETTER CHRISTMAS IN 2012'
Former U.S. House of Representatives Speaker Newt Gingrich drew some of the biggest cheers of the evening for a speech that forecast economic recovery after Obama's defeat in November 2012.
"Late that night, the recovery will begin," Gingrich said, predicting a groundswell of optimism and hiring after Obama's defeat. "We can have a dramatically better Christmas in 2012 if it is the goodbye Obama Christmas."
The social and religious conservatives who play a big role in the Iowa nominating contest on January 3 have spent much of the Republican campaign desperately seeking a candidate to rally around.
Bachmann surged during the summer but faded shortly after her August straw poll win, then faded. Perry took the lead after entering the race in August but sunk after a series of halting debate performances.
Cain is the latest candidate to surge in the race, with recent polls giving him leads in Iowa and in some cases, nationally. His supporters in the crowd said they thought he could have some staying power.
"Look how far he's come with no budget. He's charismatic, and when he says something you can believe it," said Keith Lacy, who owns two Godfather's Pizza restaurants in Cedar Rapids, Iowa. Cain had been chief executive of the pizza chain.
Bachmann told the conservative crowd she was one of them and said they needed to rally around a candidate to kick Obama out of the White House.
"This is the year when social conservatives can have it all," Bachmann said. "This is our year when we don't compromise, this is our year when we don't settle."
Former Massachusetts Governor Mitt Romney, the nominal front runner in the Republican field who on Thursday made just his third visit to Iowa this year, skipped the forum. He has had trouble winning over conservatives because of his past support for abortion rights and an individual healthcare mandate.
After plunging millions into the Iowa contest in 2008, Romney lost to former Arkansas Governor Mike Huckabee, who won strong support from the state's religious conservatives. Polls showed big majorities of caucus-goers in 2008 made up their mind in the last month before the contest.
U.S. Representative Ron Paul also spoke at the forum.
Mochila insert follows.
