BOULDER, Colorado — GOP presidential candidate and former Pennsylvania Sen. Rick Santorum is expanding his campaign, particularly in Iowa, as many others in the GOP field are cutting back.

“We’re building. We’re hiring. We just moved into a big office. We’re growing our team when others are shrinking their team because we went into this with the very clear idea that this is going to be a resource constraint,” Santorum said to a reporter in the CNBC media spin room after the debate who asked about his ground game in Iowa – the nation’s first caucus state.

Santorum’s campaign recently took over former GOP presidential candidate Wisconsin Gov. Scott Walker’s office near Des Moines, Iowa.

He explained that he is a business guy with an MBA and has overseen a company.

“You have to look at your revenue – your potential revenue – and you have to make sure you put your budgets together so you can survive, so you can get some return on that investment,” he explained.

Santorum is building his campaign as fellow GOP presidential candidate former Florida Gov. Jeb Bush – a one time frontrunner – had to scale back and make major cuts to his campaign last week.

“We built a very lean and efficient campaign and a lot of our folks are working part time – are working for a lot less money than the other hired guns that are working in the other campaigns,” Santorum said of his staff. “To be honest with you, they’re hungry – they’re as hungry as I am. They’re working hard and I feel very good that Iowa is going to come around.”

Santorum said the Republican primary is similar to the demolition derby.

“You sort of want to keep your car away from all the carnage and let the other folks just slam into each other and eventually some of the cars stop running, and you’re out there and you’re still moving. If you’re still moving, you got an opportunity to win.”