Three protesters rushed the stage as Gov. Chris Christie spoke at the Iowa State Fair's political soapbox.

They were protesting Christie's veto of a bill that would have banned the use of pig gestation crates, a technique for raising pork that some consider cruel.

State troopers pulled the protesters off the stage but not before one man shouted "Animals want to live!"

Christie said that the disruption made him feel like he was back in New Jersey. He also defended his veto of the bill and thanked protesters for giving him the chance to say so.

It was part of a wide-ranging 20-minute question-and-answer session by Christie that he launched into without delivering prepared remarks. He parried questions on President Barack Obama's Iran nuclear deal, calling it a huge mistake, and touted New Jersey's status as third in the nation in use of solar power.

Throughout his appearance, pro-immigrant protesters could be heard chanting in favor of citizenship.

On the soapbox, Christie also criticized former President Jimmy Carter's foreign policy record, making him the second Republican presidential hopeful to attack Carter's legacy within days of Carter's announcement that cancer has spread to his brain.

Christie also slammed President Barack Obama's foreign policy record and compared him to Carter, saying that Obama "makes Jimmy Carter look strong."

When asked later whether the remark was appropriate, Christie said he wasn't talking about Carter's health, but his presidency.

"We all wish the president the best, we wish for him to recover and to live a long and healthy life," Christie said, adding that his comment was about Obama and less about Carter.

On Friday, Ted Cruz criticized Obama's and Carter's administrations during a speech in Iowa, saying both suffered from the "same failed domestic policy, same misery, stagnation and malaise."

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