(CNN) - Mitt Romney's sons defended their father Tuesday against an earlier charge from rival Newt Gingrich that the former Massachusetts governor lied about his ties to negative campaign ads.
Speaking to CNN Senior Congressional Correspondent Dana Bash, four of Romney's five sons weighed in on the state of the campaign on the day of the critical Iowa caucuses.
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"You get thick skin throughout this whole process, and we know what our dad's all about," Matt Romney said when asked about Gingrich's "lying" comments. "We love him. We know he's a man of integrity. He's a great example as a father for us, so it really doesn't - we don't take it personally."
On Tuesday, Gingrich was asked on CBS if he thought Romney was a "liar" for saying he didn't have anything to do with a super PAC running anti-Gingrich ads in Iowa. Gingrich answered unequivocally "yes."
Josh Romney said each of the 2012 candidates was running in their own particular fashion.
"We're running in to a lot of great candidates running for president in their own way, but we're here to talk about my dad and why we think he's the best candidate for the president of the United States," Josh Romney said.
As for any negative campaigning against their father, Romney's sons were in agreement that the attacks came with the political territory.
"We know there are going to be a lot of tough ads. Anything that we hear said, we know who he is, he's a great man of integrity and great father and leader. We know we have to have thick skin," Matt Romney said.
Tagg Romney said the ads running in Iowa would only be the beginning.
"Politics is a tough sport. You have to be willing to take the heat. We know there's going to be a lot of negative ads coming from the Democrats in the general election and you have to be able to withstand those things," he said.
Asked if there was anything voters might not know about their father, Romney's sons listed off anecdotes from their childhoods, including Mitt Romney's penchant for playing pranks, and his love for spending time with his grandchildren.