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Donald Trump, Marco Rubio, and Ted Cruz got into a heated discussion about Israel and peace efforts with the Palestinians at Thursday's big GOP debate, with each one trying to prove they were the most pro-Israel candidate on stage.

Trump said as president, "there's nothing I would rather do than bring peace to Israel and its neighbors, generally. I think it serves no purpose to say you have a good guy and a bad guy." Trump acknowledged he may not be successful ("it's probably the toughest negotiation anywhere in the world"), and said that while he is pro-Israel, "it doesn't do any good to start demeaning the neighbors." Cruz accused Trump of having the same stance as Hillary Clinton, with both wanting to be "neutral," and said he stands "unapologetically with the nation of Israel."

Rubio pounced, saying Trump might not realize it, but "the position you've taken is an anti-Israel position. You cannot be an honest broker in a dispute between two sides, in which one of the sides is constantly acting in bad faith." Rubio said the Palestinian Authority has "walked away from multiple efforts to make peace, very generous offers from the Israelis," and the next president of the United States "needs to be someone like me who will stand firmly on the side of Israel, the only pro-American, free enterprise democracy in the entire Middle East."

Trump shot back, telling Rubio he's not a negotiator and bringing up a previous back-and-forth between Rubio and former candidate New Jersey Gov. Chris Christie. "I watched him melt down and I tell ya, it was one of the saddest things I've ever seen," Trump said. "These people may even be tougher than Chris Christie." Rubio sputtered that "the Palestinians are not a real estate deal," but Trump stood firm: "A deal is a deal."