Five Republican men who say they want to be Iowa’s next governor will gather at Drake University this afternoon for a public forum hosted by IowaPolitics.com. Gay marriage is likely to be among the issues debated.

Bob Vander Plaats of Sioux City argues gay marriage will be the defining issue of the primary campaign among the Republicans who hope to be governor.

"The people in this primary are going to ask every candidate: ‘Are you willing to issue the executive order?’" Vander Plaats says.

Vander Plaats promises that if he’s elected governor, he’ll issue an executive order that would nullify the Iowa Supreme Court opinion which legalized gay marriage.

"There’s a separation of powers thing here that needs to be debated," Vander Plaats says.

But none of the other Republicans have joined Vander Plaats in pledging to try to use executive branch power to knock down the court ruling. Governor Chet Culver, a Democrat who intends to seek reelection in 2010, says Iowa governors do not have the authority to overturn court rulings.

State Representative Rod Roberts, a Republican candidate from Carroll, says he believes in the traditional definition of marriage as being between a man and a woman, but he says an executive order won’t resolve the issue.

"I think that there are very fair, outstanding questions as to the effect that executive order would have and what the result would be and whether or not that would sufficiently be able to do what (Vander Plaats) suggests that it can," Roberts says. "The proper thing to do in this matter is to allow the people to vote."

Roberts and the other four Republican men who have filed paperwork to form "exploratory committees" to run for governor favor a constitutional amendment which would let Iowans vote to ban gay marriage. Roberts pledges to push the legislature to pass a resolution which would set the wheels in motion for that kind of a statewide vote on gay marriage.

"If that question has not been adequately addressed by the time I’m elected governor, I can tell you that in that first legislative session along with dealing with the budget and dealing with government reorganization, I will certainly make sure that resolution has been taken up and passed so the people of Iowa can vote on that issue," Roberts said Tuesday during an appearance in Des Moines.

Iowa’s governor does not have the power to put proposed constitutional amendments on the Iowa ballot. That authority rests with state legislators who must pass resolutions, twice, before proposed amendments to Iowa’s constitution can be submitted to voters.