Former Massachusetts Gov. Mitt Romney faced an angry crowd at the Iowa State Fair on Thursday, and it led to a heated exchange with the early GOP frontrunner.

A group of people attending an outdoor speech of Romney's at one point interrupted his question-and-answer session with chants of "Wall Street greed."

One questioner asked the GOP presidential candidate what he would do to strengthen Social Security. That voter didn't like Romney's pledge not to raise taxes, and interrupted him, shouting and screaming over the candidate as he tried to answer.

At one point, Romney frustratingly pointed at the crowd and told them to give him a chance to answer. After a minutes-long exchange with Romney and the crowd shouting over each other, Romney said, "If you want to speak, you can. But it's my turn."

As he wrapped up, he joked, "These guys up front won't be voting for me."

The Associated Press contributed to this report.