SHELDON, Iowa — After a 30-minute, immigration-packed stump speech, Republican presidential candidate Tom Tancredo figured that he was done talking, but his campaign chairwoman wouldn't let him sit down until he assured supporters here of his perfect 30-year voting record on pro-life issues.
In a state where "choose life" yard signs dot the mowed grass between the cornfields and country lanes, abortion can be a make-or-break issue for Republicans, both in the top tier and among those such as Mr. Tancredo looking to break out of the lower tier.
Dedicated pro-life voters make up more than 60 percent of potential Republican caucusgoers, and an even larger portion of the dedicated activists who get their family, friends and church members to turn out to vote. As a result, the issue has popped up continuously in the weeks leading up to Saturday's Iowa Republican Party straw poll.
"If you're not pro-life, you won't get their vote," said Bay Buchanan, Mr. Tancredo's campaign manager and a veteran of several Iowa campaigns with her brother, former two-time Republican candidate Pat Buchanan.
It also explains why Mitt Romney, the favorite to win this weekend's straw poll, is working overtime to defend his position on the issue.
"I'm tired of people who are holier-than-thou because they've been pro-life longer than I have," he said in Sunday's debate in Des Moines.
Mr. Romney assures voters he is now solidly pro-life and that his actions as governor of Massachusetts back that up. But it's a question he has to keep answering again and again — including just hours after the debate, at a town hall in Madrid, when even a self-identified supporter asked Mr. Romney to clarify his position one more time.
The candidates place the percentage of pro-life voters in the caucuses at 60 percent to 70 percent, and a 2006 poll of potential caucusgoers found that 61 percent said they vote pro-life while 11 percent said they vote pro-choice. Only a quarter of voters said a candidate's stance on abortion "doesn't matter."
Voters here said a pro-life position is a litmus test for a host of values and pro-family issues.
"If you don't get that position right — the pro-life position — how are you going to get a lot of them right?" said Kent Kilen, owner of the Morning Star Catholic Books and Gifts store in Milford, as he waited for Sen. Sam Brownback of Kansas, one of the plethora of candidates who claims the pro-life mantle this year.
That's not to say a pro-choice Republican candidate can't win here, just that no such strong, credible candidate has emerged in the modern era — until this year, with former New York Mayor Rudolph W. Giuliani's rise.
"If I'm Giuliani's strategist, I'm saying, there's 39 percent that this issue doesn't matter to, and George Bush won the Iowa caucuses with about 40 percent eight years ago, and Bob Dole won them with about 30 percent," said Steve Grubbs, president of Victory Enterprises, which conducted the poll of caucusgoers.
Mr. Grubbs, who is a strategist for another candidate, former Wisconsin Gov. Tommy G. Thompson, says that as secretary of health and human services, Mr. Thompson "helped forged President Bush's stem-cell policy" and has the credentials to claim the pro-life mantle.
But he gets an argument from Mr. Brownback, who says he has been the most influential of the candidates in shaping the federal debate, and from Mike Huckabee, who has attended all but one March for Life in Washington for the past 16 years. The former Arkansas governor also includes among his accomplishments a fetal-pain law, a parental-notification statute and a pro-life state constitutional amendment.
Mr. Huckabee, Mr. Brownback and Rep. Ron Paul of Texas all begin their stump speeches with a long defense of their pro-life position and credentials.
The issue even crosses party lines here in Iowa. In 2004, the Democrats' eventual nominee, Sen. John Kerry, eager to win the pro-life Catholic voters in the state's eastern part, told the Dubuque Telegraph Herald: "I oppose abortion personally. I don't like abortion. I believe life does begin at conception."
The problem for the 2008 Republicans is that they are canceling each other out — and that's prompted some interesting intraparty jibes.
Mr. Paul's campaign hands out fliers charging Mr. Brownback and Sen. John McCain of Arizona with having voted for a spending bill in 2005 that sends taxpayer dollars to Planned Parenthood, while phone-bank calls have also been made challenging some candidates' commitment.
Each of those lower-tier candidates wants a unified pro-life movement behind him because, as Mrs. Buchanan said, a campaign can build a strong grass-roots machine capable of challenging the well-funded top tier — if they have the pro-life activists.
"They're completely dedicated," she said. "They are extremely active in our party. They will be there."
Mr. Romney is the only candidate here who seems to get asked about his position regularly at town hall meetings.
Bob Vander Plaats, Mr. Huckabee's Iowa campaign chairman and the Republican nominee for lieutenant governor in 2006, said the pro-life voters here applaud someone for switching from pro-choice to pro-life, but they want to make sure.
"Iowans have a hard time seeing a gray area in the pro-life movement," he said.