WATERLOO, Iowa – It was Jolene Tagtow's 49th birthday, and Mike Huckabee surprised her last week when he concluded a rally at a local pizza parlor by urging 100 potential supporters to sing to her.

“How many people have the next president of the United States singing 'Happy Birthday' to them?” Huckabee wondered. After the last strains faded, Huckabee sought to shame Tagtow's husband into taking her to a fancy restaurant – not another pizza joint – warning that if he didn't, “You'll be wearing a frying pan on your head.”

All that special attention notwithstanding, Jolene Tagtow remained undecided, even while acknowledging that Huckabee, the former Arkansas governor, “is saying a lot of things I already agree with.”

But Tagtow said she needed to listen to candidates such as former New York Mayor Rudy Giuliani, who was due to follow Huckabee in Iowa last week.

Tagtow's ambivalence about supporting Huckabee in Iowa's Jan. 3 Republican presidential caucuses appears to mirror a central problem confronting the genial former Baptist preacher.

Despite his growing support in Iowa and admiring media attention, he has failed so far to convince party skeptics that he can win the Republican nomination and defeat the Democratic nominee.

Huckabee shrugs off his critics, saying in an interview: “The interesting thing to me is that every month somebody has written my (political) obituary. Here we are in the middle of November – we're still standing. In fact, we're not just standing. . . . We've had a steady rise and now a surge. I'd rather be where I am than where some of these other guys are.”

Huckabee promotes an inclusive political gospel that marries conservative values with an economic populism founded on Christian principles of charity, fairness and concern for the weak and underprivileged. An applause line comes when he proposes to abolish the income tax – and the dreaded Internal Revenue Service – and replace it with a national consumption levy.

After a surprising second-place finish in August's Iowa straw poll, Huckabee, 52, emerged as the principal competitor to the GOP front-runner here – former Massachusetts Gov. Mitt Romney.

But Huckabee remains substantially outgunned by Romney, whose campaign has been airing television ads in Iowa since January. Huckabee's campaign aides say they will soon do likewise, but they are vague about when.

Huckabee appears to be winning hearts, but not yet minds in Iowa. Republican activists are reluctant to support him absent a convincing showing in national polls. He remains mired in single digits in many of them.

“The main hurdle for Mike Huckabee in Iowa is viability after the caucus,” said Chuck Laudner, the executive director of the Iowa Republican Party. “The limit now, really, is . . . 'OK, even if you win Iowa, where do you go?' They have got to see that there is a chance. . . . That is his limit for climbing higher in the polls. Otherwise, he's right on the issues.”

Some Republicans who came out to assess Huckabee during an Iowa campaign swing last week underscored those concerns.

After an event in Cedar Falls, Barry Adams, 66, said: “I support him – for vice president. I think Governor Romney has a little better chance to raise the money to be president. I think Mike's time will not be in '08 but some time later to be president.”

Still, Huckabee has parlayed affability, oratorical skills honed during years in a Baptist pulpit and a knack for self-promotion to become a credible dark horse against what many Republicans consider a stable of flawed thoroughbreds – Giuliani, Romney, Arizona Sen. John McCain and former Tennessee Sen. Fred Thompson.

At the heart of his appeal is his self-advertisement as a right-winger who's not mad at anybody.

In the pizza parlor, Huckabee talked tough about cracking down on illegal immigration but added: “I thank God every day I'm in a country that people are trying to break into, not break out of. And I'm not angry at the people who want to come here.”

Analysts say the underdog optimist has pragmatic limits.

“A smile and a shoeshine can only take you so far,” said Jack Pitney, a political scientist at Claremont McKenna College. “Now perhaps there is a stealth organization that hasn't gotten a lot of attention. But absent that, it is extremely unlikely that he'll be able to overcome the disadvantages that he faces.”

One of those obstacles is hostility from fiscal conservatives, who point to his 10½-year record as governor when he cut deals with a Democratic state legislature to raise revenues for road projects and education and to improve child health care. In his defense, Huckabee notes that he championed about 90 tax cuts.

His rhetoric about the vagaries of an otherwise strong economy suggests a bleeding heart to his critics.

Repeating a line he uses often, he told a Cedar Rapids crowd that “I'm one generation away from dirt floors and outdoor toilets. . . . My ancestry doesn't open doors.”

In a dig at a former senior Bush aide who doubted whether anyone with the “hick” name of Huckabee could be elected president, the candidate drew a roar of laughter when he quipped, “Well, la-di-da-di-da.”

He also riles GOP free-trade purists by saying as president he would insist on “fair trade,” meaning penalties and trade barriers for countries such as China that use child labor and other unsavory practice.

In the interview, Huckabee pushed back against those critics.

“Is it morally responsible for me to know that I'm enjoying the low price because some 9-year-old worked 20 hours?” he said. “When economics becomes devoid of any sense of morality, then I think they are no longer justified as pure economic policies.”