Updated

One by one, five Republican candidates for president took the stage Tuesday in the state that holds the first presidential contest to pitch themselves as the strongest to challenge Democratic President Barack Obama on voters' top issue: jobs.

Absent from the forum was the one Republican who has made that argument central to his second campaign for the White House: Mitt Romney. The former Massachusetts governor, sitting atop most polls and a pile of cash, was in New York raising money.

And businessman Herman Cain took a pass, too, staying in Washington to deal with the fallout of the disclosure of sexual harassment allegations from the 1990s while he was the head of the National Restaurant Association.

So Rick Perry, Rick Santorum, Michele Bachmann, Ron Paul and Newt Gingrich looked to fill that vacuum, jockeying for relevance on corporate tax policy in hopes of gaining an edge with economic conservatives two months before the Iowa caucuses. In a GOP primary campaign with few major policy distinctions, the 90-minute forum illuminated incremental differences as the candidates worked to demonstrate savvy on voters' top concern.

Of those on stage, only Perry said he favored maintaining a tax on reintroducing corporate profits held offshore to the U.S.

"I would put a five-and-a-quarter percent rate on that money for one year, to allow it to be brought back in, to be able to create jobs," the Texas governor told the audience of about 400 at Vermeer Manufacturing, an agricultural plant, in Pella. Today the money is taxed at the 35-percent corporate rate.

Santorum, the former Pennsylvania senator, favors requiring no tax on the money if it is spent on a manufacturing plant and equipment. And Bachmann, Gingrich and Paul said they support a zero-percent tax, without strings.

"Without a doubt, it's their money," said Bachmann, a Minnesota congresswoman. "Profits are stimulus. That's the true stimulus."

All the candidates on stage called for vastly cutting federal regulations and overturning the health care law. They also support incentives — to varying degrees — for U.S. companies to bring money generated overseas back into the country on the argument the infusion of cash will spark expansion and hiring. Estimates range from $1.2 to 1.7 trillion in off-shore profits.

Studies have shown, however, that a similar holiday under President George W. Bush and a GOP-controlled Congress in 2004 and 2005 had little effect on job growth.

The forum was one of several this year in Iowa and New Hampshire, where the voting begins in January. The appearances are important for lesser-known candidates to meet voters in key early-voting states. Most of the multicandidate events in Iowa so far have been sponsored by social conservative groups, a potent force in Iowa's GOP caucus electorate. This one was put on by the National Association of Manufacturers in hopes of giving Iowans a better sense of where candidates stand economically.

But the meeting's value was unclear, considering Romney, who is stressing his decades as an investment capital firm executive as proof of his economic savvy, and Cain, who is running on his record as a businessman, weren't there. Both are running ahead of the others in national and state polls.

"The ones that weren't here were the ones that missed out," said Iowa Gov. Terry Branstad, a pro-business Republican elected again last year after a dozen years away from the office and who co-hosted the event.

Romney chose to stick with his policy not to appear with his rivals on stage, except at nationally televised debates, even though he's competing more aggressively in Iowa than he had earlier this year and is trying to win over the pro-business segment of the GOP that lifted Branstad to victory last year.

"In my book it hurts him," said undecided Iowa Republican Connie Richards, a nursing home administrator who attended the Pella forum. "If they have an economic plan to present, I want to hear it, and I didn't today."

Of all of Romney's rivals, Perry is working the hardest to emerge as Romney's chief challenge on the economy — and he has the money to do it.

But even though he had the opportunity, Perry took a pass on jabbing at Romney and focused on promoting his own plans.

"In Texas, or in Iowa, or whatever state it is, we know that the way you create jobs is not by overtaxing, overregulating or overlitigating," Perry said.

Paul, a libertarian Texas representative, ignited laughter when asked what he would like to hear Federal Reserve Chairman Ben Bernanke say at a scheduled Wednesday meeting on interest rates. "He was resigning," said Paul, who has called for the elimination of the Federal Reserve Bank.

Bachmann stressed opening international markets and declaring a moratorium on federal regulations. "We need the federal government to get off our back."

Santorum pitched his plan to eliminate the corporate income tax for companies that make products in the United States, saying: "We need to make more things in America again."

Although all the candidates sharply criticized Obama's approach to the economy, Gingrich was most aggressive, calling the president, "a left-wing radical," and arguing that unemployment compensation should require job-training.