Mitt Romney's GOP presidential rivals knew going into Tuesday's debate in Las Vegas that the former Massachusetts governor was working on cementing his lead as the most electable Republican.

Texas Gov. Rick Perry spent his time trashing Romney, who was also taking criticism from several fronts over his health care reform in Massachusetts, his job-creation record and immigration.

Yet Romney deftly neutralized the attacks, even using them to make presidential-sounding pronouncements aimed at general election voters.

When former House Speaker Newt Gingrich said that there was big government behind Romneycare, Romney shot back in response, Actually, Newt, we got the idea of the individual mandate from you.

Gingrich claimed that was false, but he eventually admitted that he had supported an individual mandate in the 1990s along with conservative think tank Heritage Foundation.

On immigration, Romney turned a discussion on ways to stop illegal immigration and touted legal immigration, saying there are more than 4 million people in line.

Romney also had some help with deflecting the attacks from Rep. Michele Bachmann of Minnesota. After getting pummeled on Romneycare for its similarities to Obamacare, Bachmann directed her attention to the health care reform law, taking the heat off Romney.

Throughout the debate, Bachmann could be counted on to remind Republicans watching and those on stage that Obama was the real problem facing America.

The good news is, the cake is baked, Bachmann said. Barack Obama will be a one-term president.

Hazing Cain

Meanwhile, businessman Herman Cain, who has moved into the top tier of candidates in some national polls, also spent most of his time fending off criticism of his 9-9-9 plan on taxes. While he was as unflappable as ever in defending his policies, his rivals were glad to poke many holes through them.

His 9-9-9 plan, which would scrap the current federal tax system in favor of a 9 percent sales, income and corporate tax, was the first target of the debate.

Bachmann said establishing a national sales tax would let Congress eventually jack the rate up to 90 percent. Former Sen. Rick Santorum of Pennsylvania called it a a major tax increase.

Romney asked Cain if people would still have to pay state sales taxes under the 9-9-9 plan.

Like all others who have attacked the plan, Cain said they were comparing apples (state taxes) to oranges (federal taxes).

And I've got a bushel of apples and oranges because I'm going to be paying for both taxes, Romney said.

Perry also got into the action, pointing out all of the major purchases Americans make that would carry an additional 9 percent tax. He also promised to offer his own tax plan this week.

I'll bump plans with you, brother. And we'll see who has the best ideas, Perry told Cain.

Later in the debate, Cain doubled down on his comments on Occupy Wall Street protesters -- he said they should blame themselves for being jobless -- when given an opportunity to pull them back.

I still stand by my statement, Cain said. They're directing their anger at the wrong place. Wall Street didn't put in failed econ policies. ... They ought to be over at the White House taking out their frustration.

Cain also took a shot at Romney's Wall Street business background, saying that his business experience was more Main Street.

I have managed small companies. I have actually had to clean the parking lot, Cain said.

Perry and Romney Tussle

Perry's past performances at debates have been lackluster, helping drive his once-high poll numbers down, on par with libertarian Rep. Ron Paul of Texas. He tried to fashion himself as the true conservative, in an effort to win support from the Republican base seeking an alternative to Romney.

At Tuesday's debate, Perry tried to knock Romney off his perch in the front of the pack by attacking his record as governor, his health insurance plan and even dredging up an old story about Romney hiring illegal aliens.

Romney said -- after multiple interruptions from Perry that led Romney to put his hand on his rival's shoulder -- that a landscaping company he hired to work on his home had employed illegal immigrants but he eventually fired the company.

Perry constantly highlighted his job-creation record and his plan to boost employment through increased oil production.

We've got 300 years of resources right under our feet in this country, Perry said.

For his opening remarks, Perry said that he is an authentic conservative, not a conservative of convenience, a shot at Romney for his changing positions on issues such as abortion.

Ron Paul Maintains Libertarian Cred

Paul maintained faithful adherence to his libertarian beliefs, stuck to policy and refrained from attacking his opponents.

When asked about military cuts, Paul said America would still be safe with less funding, suggesting that soldiers in Germany and Japan be brought home. He also suggested cutting all foreign aid, including to Israel, which he said would benefit by regaining its  sovereignty.

He also spent time railing on the U.S. Federal Reserve, a favorite whipping boy. He said that the Fed, not bankers, were to blame for the financial crisis.

They create the financial bubbles, Paul said. And you have to understand that you can't solve these problems if you don't know where these bubbles come from.