SIMI VALLEY – Texas Gov. Rick Perry, the surging presidential candidate joining the Republican field Wednesday for the first time on a national stage, touted his record on job creation and defended his view that Social Security is a "Ponzi scheme" for future generations.

His chief rival, former Massachusetts Gov. Mitt Romney, used the prime-time debate to suggest that Perry's jobs claims are overblown and took him to task for his rhetoric on Social Security, saying "under no circumstance would I ever say … it's a failure."

Perry, who entered the race in mid-August, is challenging Romney atop a crowded field of Republican candidates. He is a relative unknown to Republicans, both nationally and in California.

But the folksy, socially conservative Perry has made inroads in the Golden State, polling even with Romney among Republican voters here. Even before he became a presidential hopeful, Perry poked at California's liberal policies and boasted about the jobs he lured to Texas.

"If, you know, you want to live in a state that has high taxes, high regulations, that is favorable toward smoking marijuana and gay marriage, move to California," Perry told National Public Radio last year.

He also claimed last year that Texas had taken 153 businesses from California in the first eight months of the year. But critics question the amount of credit he deserves for Texas' job growth.

Romney said Perry benefited from Texas' natural resources, Republican Legislature and conservative policies.

"Those are wonderful things, but Governor Perry doesn't believe that he created those things," Romney said. "If he tried to say that, well, it would be like Al Gore saying he invented the Internet."

Romney, the front-runner before Perry joined the race, largely focused on President Barack Obama and avoided sparring with his Republican opponents in previous debates. But with Perry beside him, that luxury was lost.

He directly challenged Perry's comments on Social Security, saying, "you can't say that to tens of millions of Americans who live on Social Security and those who have lived on it," Romney said. "The governor says look, states ought to be able to opt out of Social Security. Our nominee has to be someone who isn't committed to abolishing Social Security, but who is committed to saving Social Security."

Perry didn't budge, calling the program a "monstrous lie to our kids."

"You cannot keep the status quo in place and not call it anything other than a Ponzi scheme," he said. "It is. That is what it is. Americans know that."

Perry also faced questions about his views on climate change, on which he said the science is "not settled."

Former Utah Gov. Jon Huntsman did not specifically mention Perry, but he said, "Listen, when you make comments that fly in the face of what 98 out of 100 climate scientists have said, when you call into question the science of evolution, all I am saying is that, in order for the Republican Party to win, we can't run from science … . We've got to win voters."

The one-hour, 45 minute debate was heavily colored by the nation's weak economy, with unemployment still above 9 percent. Obama is viewed as a vulnerable incumbent, and the Republicans criticized his policies Wednesday on health care, the economy and immigration.

"For the president of the United States to go to El Paso, Texas, and say that the border is safer than it's ever been, either he has some of the poorest intel of a president in the history of this country, or he was an abject liar to the American people," Perry said. "It is not safe on that border."

Obama will appear on national TV this evening, when he is scheduled to announce a jobs creation plan.

The heavy focus on Romney and Perry irritated at least one contender, former House Speaker Newt Gingrich.

"Well, I'm frankly not interested in your effort to get Republicans fighting each other," he said when asked about the front-runners' differences on health care. "Whoever the nominee is, we are all for defeating Barack Obama."

Though still early in the contest, Perry's presence has upended the dynamic of the Republican contest ahead of primary elections next year.

In addition to challenging Romney atop the field, Perry has siphoned tea party support from Rep. Michele Bachmann of Minnesota, who has fallen back after winning the Republican straw poll in Iowa.

Bachmann stayed largely out of the fray on Wednesday, focusing her remarks on Obama, including criticizing his health care overhaul.

"I've raised five biological kids and 23 foster kids in my home," Bachmann said. "One thing I know is that kids need jobs. And Obamacare is clearly leading to job-killing regulations, not job-creating regulations."

Also debating were Texas Rep. Ron Paul, former Pennsylvania Sen. Rick Santorum and former Godfather's Pizza chief executive Herman Cain.

California is so heavily Democratic that no Republican is likely to campaign earnestly against Obama here. But California is a major donor state, and Perry is looking to raise money as he tries to catch up to Romney in fundraising.

Perry has a series of events scheduled in California today and Friday. Bachmann and Romney also have events planned in Southern California.

The debate was the first of five this month and next. A narrowed field of Republicans is expected to return to the Reagan Presidential Library next spring, when the stakes will be significantly higher.

The hilltop setting invited frequent references to Reagan, California's centrist former governor.

"President Reagan wrote in his diary," Gingrich said during an exchange on immigration and a measure Reagan signed, "that he signed the act because we were going to control the border and we were going to have an employer program where it was a legal guest worker program. That's in his diary." Gingrich said, "I'm with President Reagan."

© Copyright The Sacramento Bee. All rights reserved.

Call David Siders, Bee Capitol Bureau, (916) 321-1215. Follow him on Twitter, @davidsiders.

• Read more articles by David Siders