One issue that Gingrich's rivals subtly tried to exploit during the debate was his personal history of three marriages and an admitted extra-marital affair.
Perry, who has been running ads in Iowa touting his family values and long-time marriage, took a veiled jab at Gingrich, telling the audience, "If you cheat on your wife, you'll cheat on your business partner, so I think that issue of fidelity is important."
Santorum said he believes "character" is important as an issue for voters to consider, before Gingrich was finally given the opportunity to respond.
Voters need to "have a feeling that this is a person that they can trust with the level of power we give to the presidency," he said. "I think people have to render judgment -- I've said in my case, I've made mistakes at times -- I'm also a 68-year-old grandfather and I think people have to measure what I do now."
Halfway through the debate, the spat between Romney and Gingrich flared over the issue of Israel and personal friendship with Israeli Prime Minister Benjamin Netanyahu.
Gingrich defended the controversial comments he made Friday, when he said the Palestinian people were "invented." He said tonight that his statements were "factually correct."
"Is it historically correct? Yes. Are we in a situation where every day rockets are fired into Israel while the United States -- the current administration, tries to pressure the Israelis into a peace process. Hamas does not admit the right of Israel to exist and says publicly not a single Jew will remain," Gingrich said.
"It's fundamentally time for somebody to stand up and say enough lying about the Middle East," he said.
Romney said Gingrich's comments were reckless, and that he was speaking for Israel.
"Israel does not want us to make it more difficult for them to sit down with the Palestinians. Ultimately, the Palestinians and the Israelis are gonna have to agree on how they're gonna settle the differences between them," he said. "And the United States of America should not jump ahead of Bibi Netanyahu and say something that makes it more difficult for him to do his job.
"We don't negotiate for the Israeli people," Romney said. "We stand with the Israeli people, stand with our friends, and make it very clear. We're going to tell the truth, but we're not going to throw incendiary words into a -- a place which is -- a boiling pot when our friends the Israelis would probably say, 'What in the world are you doing?'"
Gingrich retorted that he "did not speak for the people of Israel, I spoke as a historian," adding he has known Bibi Netanyahu since 1984, calling the Israeli prime minister by his nickname.
Romney countered, "I've also known Bibi for a long time," adding that they worked together at Boston Consulting Group.
"I will exercise sobriety," Romney said. "I wouldn't do anything that would alter this process. Before I do that, I get on the phone with my friend Bibi Netanyahu."
When Perry was given the chance to speak, he called the uproar over Gingrich's remarks a "minor" issue blown up by the media, channeling Gingrich's attacks on the media from other debates.
"This president is the problem, not something that Newt Gingrich said," he said.
Later, the candidates were asked about their childhood struggles and experiences through which they can identify with economically struggling Americans.
Romney admitted he "didn't grow up poor," but said his parents -- his father was the governor of Michigan, George Romney -- instilled a strong work ethic in their children because he "grew up with a dad that was poor."
Bachmann told a story she's told before, recounting her parent's divorce, which she called a "tragedy" that so many families in the country go through.
"My mom was a fulltime homemaker with four kids and we went below the poverty line overnight," mentioning that she had to start working at a young age.
"I know what it's like for single moms to struggle," Bachmann said. "We are still coupon-clippers today. ... We get what that feels like."
The very last question thrown at the candidates was what they have learned from one of their onstage rivals.
Santorum said that as a 30-year-old running for Congress -- he won his first race at 32 -- listening to Gingrich's audio tapes helped him.
Perry said it was his fellow Texan, Paul, who got him first "intrigued in the federal reserve."
"Congressman Paul is the individual on the stage that got me the most interested in a subject that I found to be quite interesting and at the root of a lot of the problems we have," Perry said.
Romney chose not to mention another candidate he learned from, but said he admired the movement that Paul has inspired, mentioning that when he goes to a debate the only signs he sees, even in the freezing cold, are Ron Paul signs.
"That enthusiasm in people, that's exciting to watch," Romney said.
Gingrich said the governor of Iowa, Terry Brandstad, who was sitting in the second row, was his role model, although not an opponent.
"Terry Branstad is my role model. Get outta politics for a while doin' something else, be involved in health care, come back when you're clearly too old, too experienced, too tied to the past, win the governorship decisively, do a great job," Gingrich said before also praising Rick Santorum "consistency and courage on Iran."
"If we do survive, it will be in part because of people like Rick who've had the courage to tell the truth about the Iranians for a long time," Gingrich said.
Bachmann mentioned a rival not on the stage: Herman Cain, who left the race last week.
"You can't have a debate without saying '999' in the debate," she said. "I think one thing that he showed us is the power of being very plain spoken."
So, Bachmann concluded, "I'm going to go with 'win, win, win' instead of 999."