(CBS) This analysis was written by CBSNews.com senior political editor Vaughn Ververs.
Fresh from the triumphs of two newcomers in Iowa, presidential candidates in both parties put on intense, do-or-die debates in New Hampshire just three days before that state's primary. Three Democratic candidates are now engaged in a tight race that has captured the imaginations of voters and they confronted each other head on. The Republican field is still more scrambled and so their debate was less focused, though Mitt Romney was the chief target of attacks.
It took little time for twelve months of tension between the top three Democratic candidates to burst out into the open. Coming off a loss in Iowa and badly needing a win in New Hampshire, Hillary Clinton wasted little time in going afterBarack Obama, sparking a blunt discussion about the basic dynamic of this campaign - change versus experience.
Accusing the Illinois senator of changing positions on health care and funding for the Iraq war, Clinton said "what we're looking for is a president we can count on." Obama responded, "I have been entirely consistent."
John Edwards appeared to be looking to help deliver a knockout punch to Clinton, saying that Clinton's questioning of Obama is "not the kind of discussion we should be having." Edwards tied himself to Obama as an agents of change and cast Clinton as part of the status quo fighting change. Edwards pointedly accused Clinton of attacking Obama after her loss in Iowa. Clinton loudly interjected, saying, "making change is not about what you believe, it's not about a speech to make, it's about working hard. … I'm not just running on a promise of change, I'm running on 35 years of making change."
It led Bill Richardson, the only other candidate invited to the debate, to quip, "I've been in hostage negotiations that are a lot more civil than this."
When asked about the view that she is unlikable and Obama very likable, Clinton responded by saying, "I don’t think I'm that bad." Clinton actually said that the question hurt her feelings, a rare moment of vulnerability for a candidate often described as tough and robotic.
The New York Senator benefited from the reduced field - this debate had just four candidates instead of the usual seven or eight. Fewer participants meant more time for her to elaborate on her more complex argument of experience and to show off her policy chops.
Clinton took the opening question to again try and demonstrate her depth on the issue of Pakistan. Clinton laid out a series of considerations that would have to be taken into account before the United States moved into Pakistan to get Osama bin Laden, something that Obama has said he would advocate. In response, Obama again cited the decision to invade Iraq - and indirectly Clinton's vote for to authorize the war - as being an important reason why Pakistan has been ignored.
All the candidates tried to straddle the line when asked what they would do the day after a hypothetical nuclear attack on a U.S. city, almost as if they didn't want to sound too much like President Bush. Edwards said he would retaliate against whoever was proven responsible but cautioned that a president should not over-react. Obama agreed about retaliation but said in order to prevent it, the nuclear non-proliferation treaty needs to be revitalized. Clinton went a bit further, saying that nations who allow terrorists to operate within their borders should be on notice that they will face retaliation.
In the most aggressive debate of this campaign to date, the dynamic was new. It now appears to be two-on-one battle, as Edwards tries to hitch his wagon to Obama's message of change. Clinton did not alter her insistence on the virtues of her experience. Time after time, Clinton made her case with increasing vigor.
According to the network entrance polls in Iowa, the "experience" argument was a losing one. New Hampshire voters will reach their verdict on Tuesday.
Among Republicans, Mitt Romney took by far the most incoming fire - and the most personal. Time and again, Romney's changes of position on key issues were the targets of enemy fire.
At one point in a discussion over foreign policy, Romney said to former Arkansas Governor Mike Huckabee, "Don’t try and characterize my position." Huckabee: "Which one."
Later in the evening, after Romney described himself as the candidate of change in the GOP field, John McCain said, "We disagree on a lot of topics, but I agree, you are the candidate of change." Romney at times appeared exasperated at the attacks, saying, "The continued personal barbs are interesting but unnecessary."
McCain engaged in a long, heated debate with Romney on immigration. It's one issue that has dogged McCain throughout the campaign. McCain argued with Romney over whether his support for the now-defunct immigration reform bill amounted to amnesty. When Romney insisted his television ads did not describe McCain's position that way, McCain bristled "you can spend your whole fortune on these attack ads, but it doesn't make it true."
Huckabee, the big Iowa winner, spent most of his air time, which wasn't much, on defense. He had to explain, for example, his past criticism of the Bush administration's foreign policy as "arrogant." Huckabee was quick to assure GOP voters that he supported President Bush on the war in Iraq and asserted he was among the first to support the current troop surge strategy. "When I made those statements, there were times that we gave the world the impression that we were going to do whatever we wanted to do," he said.
Rudy Giuliani and Fred Thompson, unlikely to be key factors in New Hampshire's primary, appeared relaxed. Thompson frequently chimed into the discussion with asides and comments and gave some of his most comprehensive answers to date on health care reform and foreign policy. Giuliani once again used Ron Paul as a foil on national security issues and chimed into the immigration debate by pointing out that the GOP's modern-day patron saint, Ronald Reagan, once issued amnesty to illegal immigrants.
In New Hampshire, Romney and McCain are locked in a battle in which a loss could spell the end of either campaign. McCain came out on top of this battle, if only because Romney was besieged by all sides.
But even if one of those two fall in New Hampshire, the overall picture will stay foggy. Moving on to South Carolina, Florida and the mega-state primaries on February 5th, a case can easily be made for one of at least four of the men on stage for winning the nomination. Only at the moment, the cases are slightly stronger for Huckabee, McCain and Giuliani than Romney.
In an interesting twist, Obama became a big part of the Republican debate, with candidates seeking to tie themselves to his campaign message. Romney noted that he and Obama are the candidates talking about "change." Mike Huckabee spoke of the desire among voters for the kind of "vertical" leadership the Democrat is offering. Ron Paul went to far as to claim he and Obama are very similar because they both have attracted young people to their campaigns.
Unlike Hillary Clinton, who Republican candidates are quick to use as a foil, Obama received nothing but praise from Republicans.