Let’s be honest: Mitt Romney only needed to avoid a complete meltdown in order to “win” the debate in South Carolina, that is to keep his campaign on track. He did that thanks, once again, to opponents who lacked the focus to pin him down on points on which he is vulnerable.

Romney was at his best in defending himself on his Bain work, explaining how he worked against the tide of steel plant closings and overall created 120,000 jobs (gross) at some of the companies in which Bain invested. He was smooth and effective on that, an indication that he has now been properly alerted to the necessity of defending his business record.

On releasing his tax returns, he qualified and hedged, finally saying he’s probably going to release them in April (in other words, some time after he has wrapped up the nomination). Oddly, Rick Santorum chose to take on Romney over voting rights for felons, objecting to a Romney-supporting super PAC ad saying Santorum had voted to give felons voting rights once certain conditions were met. They went back and forth for a bit. But what was the point? It’s not like allowing felons to vote is popular with Republican voters.

Romney was particularly strong in defending the U.S. presence in Afghanistan, criticizing peace talks with the Taliban, attacking President Obama’s defense cuts and agreeing with the permanent detention of enemy combatants. He was quizzed on his position on entitlements and gave a specific answer on his plans for social security, Medicare and Medicaid. Later in the debate, Romney got a strong hit in on Newt Gingrich’s super PAC “King of Bain” ad which has been widely discredited. (When asked about his hunting activities, he gave a nervous answer mixing up moose and elk.)

Gingrich was not about to go negative during the debate Monday night and was at pains to stay away from the Bain attacks. He seemed weak and defensive when quizzed about his attacks, pleading that he had only been asking some questions. But Gingrich had very strong moments as well, taking on moderator Juan Williams’s insinuation that his comments promoting a work ethic and about food stamps were anti-black. Gingrich denied the charge and took on liberal political correctness. He managed to work the Declaration of Independence in there as well. Gingrich also gave a strong defense of the killing Osama bin Laden. One wonders why he spent so much time up until now on Bain and not on flashing his conservative rhetoric.

Unfortunately for him, Santorum found himself overshadowed by Gingrich, Romney and even Texas Gov. Rick Perry. Santorum was solid when talking about his experience in fighting poverty and the role of religious groups in providing services and youth mentoring. Santorum also gave compelling answers on his tax cut plan and his zero-rate income tax for manufacturing companies. He ably defended his record on the Second Amendment, pinning Rep. Ron Paul (R-Tex.) back on his opposition to liability protection. However, it is somewhat inexplicable that he chose to take on Paul, rather than drive the debate back to Romney.

Santorum needed a breakout moment, but he didn’t get it. He’ll have one more shot on Thursday night to break away from the other not-Romneys.

Texas Gov. Rick Perry was as strong and folksy as he has been in debates. He went on a tear against the administration for its response to the Marines in Afghanistan who urinated on dead Taliban fighters. “You know what’s despicable? Cutting Danny Pearl’s head off and showing it on TV,” Perry said. Perry landed no clear blows on his opponents, however, and it is hard to see how the debate will affect his results Saturday. At one point he got a bit carried away with his attack on federal encroachment on the states, shouting, “South Carolina is at war with the federal government!” Well, that was a long time ago.

Paul likely hurt himself by running on and on about his opposition to military spending (which he said is different than “defense” spending which pays for all our troops after we’ve brought them home). He hit Santorum for votes on No Child Left Behind and against right-to-work legislation. (Santorum weakly allowed that he voted against right-to-work law because his state was not a right-to-work state. Huh? Republicans are generally in favor of right to work laws and believe they improve the economic climate of a state.)

Winners: Romney — for a strong second half and committing no real errors; Gingrich — for showing what he can accomplish when he stays on his red-meat conservative message.

Losers: Ron Paul — losing votes on national security; Rick Santorum — lost opportunities.