In what was quite possibly the most contentious of the GOP presidential debates, Tuesday night's Western Republican debate in Las Vegas illustrated how high emotions are running among the leading candidates, who at times behaved like schoolchildren arguing at recess. Former Massachusetts Gov. Mitt Romney and Texas Gov. Rick Perry sparred in the evening's tensest moments, while surging Herman Cain stayed mostly above the fray and former House Speaker Newt Gingrich came off like the adult in the room.The biggest takeaway from this encounter ought to be: Bickering is not presidential.Mr. Cain's 9-9-9 tax reform plan came under early fire from all his rivals but the focus soon shifted to Mr. Romney when he and former U.S. Sen. Rick Santorum argued over Mr. Romney's health care plan in Massachusetts. Gingrich was pulled into the fray for a moment when Romney charged he got the idea from the former Speaker and the Heritage Foundation.Later, Mr. Perry and Mr. Romney tangled on immigration. Mr. Perry said to Mr. Romney, “You hired illegals in your home and you knew about it for a year, and the idea that you stand here before us and talk about that you're strong on immigration is the height of hypocrisy.” After some shouting over each other Mr. Romney told Mr. Perry, “You have a problem with allowing someone to finish speaking. And I suggest that if you want to become president of the United States, you have got to let both people speak. So, first, let me speak.”The number of times Mr. Romney said “Let me speak” was indicative of the bickering rampant in the debate. Unfortunately, it denied voters a deeper look into the records, philosophies and plans of the candidates. The debate was also disappointing because a number of topics were left mostly unmentioned, such as education and the housing crisis.One highlight of the evening though was when Mr. Romney rattled off several ideas for cutting the federal budget. He said he would bring back discretionary spending to 2008 levels; “get rid of Obamacare,” turn Medicaid back to the states and “cut federal employment by at least 10 percent.” Most encouraging of the list, Mr. Romney said, “We say to federal employees: You're not going to make more money than the people in the private sector who are paying for you. We link their compensation.”Even though the audience was clearly pro-Romney (polls show Mr. Romney as the decisive frontrunner in Nevada), the big winners of the night were Mr. Cain, who was able stay mostly out of the bickering and avoid further scrutiny of his candidacy, and Mr. Gingrich, who sounded the most cerebral of the group.Rep. Michele Bachmann said at the end of the debate, “The good news is, the cake is baked. Barack Obama will be a one-term president; there's no question about that.”While unpopular, President Obama is far from an underdog for reelection and to underestimate him, especially when the Republican GOP nominees are bickering like schoolchildren, is naïve. As Gingrich said, “Maximizing bickering is probably not the road to the White House.” His GOP rivals should heed his message.