PELLA, Iowa—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.