Los Angeles (CNN) -- Debate newcomer Texas Gov. Rick Perry and former Massachusetts Gov. Mitt Romney clashed over their job creation records, health care and Social Security at the Republican presidential debate Wednesday night.

"When I came in as governor, we were in a real free-fall," Romney said. Unemployment was 4.7% when he left office, the former GOP front-runner said.

Perry said his opponent had a great record creating jobs in private business, but not so much as a political leader. The Texan said he helped create 1 million jobs in a decade.

Romney countered that Texas had advantages over Massachusetts, including no income tax, the oil and gas industry, and fewer unions.

The eight Republican hopefuls said President Barack Obama doesn't understand how to fix the economy.

Minnesota Rep. Michele Bachmann, a tea party favorite who won the Ames straw poll in Iowa last month, said health care reform legislation passed under Obama's leadership is hurting job creation and should be repealed.

Romney criticized Perry over his anti-Washington book titled "Fed Up."

In it, Perry refers to Social Security as a "Ponzi scheme" that could make him vulnerable to Democratic attacks in a general election campaign if he wins the Republican nomination.

"A candidate should be committed to saving Social Security," Romney said.

Perry stood by the "Ponzi scheme" remark, saying "maybe it's time to have provocative language" because the current Social Security system will fail younger workers.

GOP strategist Karl Rove called Perry's Social Security comments "toxic" in an interview Wednesday morning on ABC's "Good Morning America."

On the issue of immigration, former Pennsylvania Sen. Rick Santorum said it is vital for America -- when done legally. Romney said business and institutional incentives that draw illegal immigrants should be curbed while Perry said more troops are needed on the Mexican border.

Romney came under criticism for individual mandates in Massachusetts health care reform, but he said it was needed because too many people were getting taxpayer-funded care at hospitals.

Perry said Texans "would like to see the federal government get out of their business."

In a surprising turn, he praised Obama for the recent operation that tracked down and killed Osama bin Laden.

"I tip my hat to him (for getting bin Laden)," Perry said.

The usually tough-talking Texan added that Obama should be commended for keeping the U.S. detention facility at Guantanamo Bay, saying "America's safer for it."

The Republican hopefuls debated at the Ronald Reagan Presidential Library in Simi Valley, but all eyes were on the new kid -- Perry -- who has rocketed to the top of the polls since joining the race last month.

Perry, a favorite of tea party conservatives who also appeals to the religious right, came under attack at times from his rivals at the debate sponsored by NBC News and Politico. It was Perry's first debate appearance, while the other candidates have faced each other a few times.

NBC News anchor Brian Williams and Politico editor John Harris moderated, with Perry joined onstage by Romney, Bachmann, former House Speaker Newt Gingrich, Texas Rep. Ron Paul, Georgia businessman Herman Cain, former Utah Gov. Jon Huntsman and Santorum.

Most of the criticism of fellow candidates was aimed at Perry and Romney. Overall, the candidates tended to lambaste Obama, with knocks for his policies on energy, Libya, the minimum wage and health care reform.

Obama, Bachmann said, has weakened the U.S military presence across the globe and isn't doing enough to ensure Iran doesn't have arsenal nuclear arms.

Gingrich drew applause when he said defeating Obama is the party's top goal. Both he and Romney said Federal Reserve Chairman Ben Bernanke would not serve in their administrations.

Santorum touted his record on welfare reform: "We will transfer this system from a dependency system to a transitional system."

Paul spoke of too much federal regulation and Cain proposed ending the current federal tax code. Huntsman hammered away at job creation and said the Department of Homeland Security has created a fortress mentality in America.

"I'm here to tell you, I can get elected," Huntsman said, "I can bring the numbers together to make this successful in 2012 and I can lead based upon where I have been as governor."

Unfortunately, the most recent polling numbers are against him. Huntsman, the former U.S. ambassador to China, is barely registering in recent national polls.

The debate is one of seven such events that will take place by the end of the year, including the next one -- the CNN tea party debate on Monday.

CNN's Martina Stewart, Jim Acosta, Phil Gast and Erika Dimmler contributed to this report.