“The people who have ignored Iowa have generally not done well in subsequent states,” Branstad said.

This was the second occasion is an many days that Branstad has attacked Romney for not campaigning harder in the state, telling the Huffington Post Tuesday that Romney might finish as low as fifth or sixth in the Iowa caucus.

"I think he's going to have to put a real effort in here or he's going to be embarrassed," Branstad said. "He's trying to downplay it and keep the expectations down. But if he comes in fifth or sixth here, I think it really damages his campaign nationally. Iowa voters are spoiled by attention, and if you have a candidate who does not take them seriously, I think they'll punish him."

According to the latest poll from Bloomberg, Romney finds himself tied around 20 percent with Herman Cain, Ron Paul, and Newt Gingrich among likely Iowa caucusgoers. But Branstad told the Huffington Post "that's not going to last if he doesn't spend a lot more time and put a lot more effort in here."

Romney has instead focused his efforts on early voting states like New Hampshire and Nevada, where demographic and cultural advantages could help the candidate post early and decisive victories. But the campaign seemed to acknowledge that they could not entirely afford to ignore Iowa, announcing Monday that the former Massachusetts governor would head to the Hawkeye State next Wednesday for campaign events.

Still, state leaders are miffed that Romeny has not spent more time and effort in the state; in addition to the candidate forum that Romney plans to skip this weekend, he also missed major conservative events in October and earlier this month and will not be attending a birthday party for Branstad on Thursday.

— Andrew Restuccia contributed to the reporting of this article.