10:45pm ET: Asked about Puerto Rico and its financial difficulties, Marco Rubio dismissed the idea of changing regulations to allow the island bankruptcy protection.
“Bankruptcy protection doesn’t work unless you change the way you operate,” Rubio said. “You’re only going to go bankrupt again.”
The idea, the Florida senator said, was to first put into place austerity measures to get the island’s finances under control. “The leadership on the island has to show that they are willing to put their house in order,” he said.
10:30pm ET: In a lively exchange on national security and foreign policy, all the GOP candidates stressed that are pro-Israel, although Donald Trump was attacked for saying that he would try to broker a deal between Israel and Palestine. "If I could bring peace,” Trump said, “It would be one of my greatest achievements as president."
Marco Rubio and Ted Cruz both pushed back on Trump, asserting that negotiating with Palestine was a way to undermine Israel. “The Palestinians are not a real estate deal,” Rubio said.
“Marco is not a negotiator,” Trump countered.
"Here's what the Palestinians do,” Rubio added, “they teach their 4-year-old children that killing Jews is a glorious thing."
Trump insisted, “There is nobody on the stage who has done more for Israel than I have.”
Then he added, pointing first at Rubio and then at Cruz, “This guy is a choke artist, and this guy’s a liar.”
10:10pm ET: Marco Rubio and Ted Cruz both took Donald Trump to task about health care and whether he would repeal “every word” of Obamacare or not.
Rubio said, "I will repeal it as president and we will replace it with something substantially better for all Americans."
Rubio ribbed him for not having a full plan, simply saying that he would “remove the lines around the states” in order to increase competition among health insurance companies.
Asked point-blank if he had anything to add, Trump said, “No.”
“Did you just repeat yourself?” Rubio said, referring to his notable problem when confronted by Chris Christie at a previous GOP debate.
Trump countered, “I watched you fall apart…”
“I just watched you repeat yourself five times in five seconds,” Rubio jumped in.
Cruz then took the baton and pressed Trump on previous support for the idea of single-payer system.
The Texas senator then repeated his vow to "repeal every word of Obamacare."
Cruz says at Thursday's GOP debate that, "for decades, Donald has been advocating socialized medicine."
9:37pm ET: Ted Cruz and Marco Rubio took questions about if the two candidates are missing an opportunity to embrace their Latino heritage by fighting about who is tougher on illegal immigration. Both are Cuban-American.
Cruz is the first Latino candidate to ever win a presidential primary contest - the Iowa caucuses this month. He agreed that his candidacy "really is an embodiment" of opportunities in the U.S.
He said there is a misperception that Latinos must all be liberals. "I am fighting so that everyone who is struggling in the Hispanic community and beyond will have a fair and even shake at the American dream," he says.
Rubio also said that President Barack Obama's policies are not working for Latinos. "We have to move past this sentiment that the Hispanic community only cares about immigration."
Rubio pointed to Carson, an African-American, as well as himself and Cruz and said, "I do think it's amazing. We are the party of diversity, not the Democratic Party."
9:30pm ET: Donald Trump mocked Ted Cruz, saying he "should be ashamed" that none of his Republican Senate colleagues have endorsed his campaign for president.
The New York billionaire said the Texas senator didn't have the backing of any senators "even though you work with these people. You should be ashamed of yourself."
Cruz responded that, "if you want to be liked in Washington, that's not a good attribute for being president."
Trump then likened Cruz to Robin Hood and reminded the audience that Cruz failed to disclose about $1 million in past campaign loans from Wall Street banks.
This exchange came after Cruz accused rival Donald Trump of being late to the game on immigration.
Cruz said at the Republican presidential debate that while he was running for Senate and promising to lead the fight against "amnesty," Trump was busy donating cash to a group of senators backing a path to citizenship.
Cruz said, "Where was Donald? He was firing Dennis Rodman on Celebrity Apprentice."
He added, "When you're funding open border politicians, you shouldn't be surprised when they fight for open borders."
9:20pm ET: It didn't take long for the fireworks to start on the debate stage on Thursday night.
The topic of immigration fired up the candidates. Donald Trump said as president he would deport people living in the country illegally, but may allow some to eventually come back.
"They have to come back through a process," Trump said, "and it may not be a quick process."
Ted Cruz rejects that idea, and says he does not believe it is fair to allow anyone who has come into the country illegally to come back.
It's "a mistake to forgive those who break the law," he said.
He believes such immigrants are causing job loss and driving down wages for citizens and people who immigrated legally alike.
Marco Rubio and Trump are also mixing it up on Trump's history of hiring immigrants who are in the country illegally to work on his properties.
8:39pm ET: As the GOP Debate kicks off, it appears to be Marco Rubio and Ted Cruz's last chance to slow Donald Trump's momentum before Super Tuesday next week.
The Thursday night debate in Houston takes place just a few days before 11 states hold GOP contests that could cement Trump's dominance of the Republican race for president.
The billionaire businessman in on a three-state winning streak. Left standing on stage to challenge him are the two freshman senators, along with Ohio Gov. John Kasich and retired neurosurgeon Ben Carson.
Thursday's debate broadcast on CNN and Telemundo is the only one of the season aimed at a Spanish-speaking as well as English-speaking audience, so immigration could be the issue on which the debate turns.