The Republican debate in New Hampshire this evening will have the highest stakes, the biggest impact, and the greatest possibility for game changers of all of the matchups so far this cycle — at least until tomorrow morning, when the candidates will meet again for another debate on NBC News and “Meet the Press.”

As routine as debates have become, they continue to generate event-sized audiences for the news networks and broadcasters’ news divisions. In general viewership has been building, reflecting growing interest in the process, and there’s every expectation that will be the case tonight.

The biggest change is the size of the field: Michele Bachmann, who dropped out, means that only men will occupy the stage. But there’s every expectation that the kind of stinging attacks she offered in previous debates will be taken up by the other candidates against Mitt Romney.

6:01: “The stakes couldn’t be any higher,” ABC News says in the intro. What did I tell you? Once again, the debate is starting like a football game — there is a playoff game going on on NBC — although in contrast to past forums, ABC News’ opener is actually restrained.

6:03: Mitt Romney: “The president is going to take responsibility for things getting better. You know, it is like a rooster taking responsibility for a sunrise.”  This is in response to a question about an improving jobs picture. Romney’s argument in case there is significant job growth is that the recovery was mismanaged — and could have happened a lot quicker. But he’s also blamed Obama when the economy was not getting better. No credit for improvement, but blame when it is bad. Welcome to politics.

6:11: Jon Huntsman seems to be reintroducing himself, aware that the audience is larger. He outlines his record as governor of Utah, which has helped him earn the endorsement of the Boston Globe. But the question is whether he can make an impact in a six-candidate panel.

6:13: The first zinger of the night. Ron Paul starts speaking and he bell goes off, apparently by mistake. Rick Santorum shoots: “They caught you not telling the truth, Ron.” Paul glares at him before going on.

6:17: Santorum says, “I’m a conservative, not a libertarian.” He’s defending his record, including earmarks, but also trying to contrast himself with Paul. “I don’t vote against everything like, you, Ron.” This so far is much more a battle of the non-Romneys.

6:19: Ron Paul is challenging the notion that Rick Santorum is a Tea Partier, noting that he voted for a balanced budget amendment yet voted to increase the debt ceiling four times. Santorum says, “Routine debt ceiling increases have happened in this country over the course of 200 years.”

6:21: Huntsman once again outlines his experience, this time including his stint as U.S. Ambassador to China. He’s tried to rise above the fray at most debates, but has seemed to drift away from the competition, too.

6:27: Paul won’t take back calling Newt Gingrich a “chicken hawk.” Newt: “Ron Paul makes a lot of comments. It’s part of his style.” Later, Gingrich gets more feisty and says that he “resents” Paul’s attacks and that he “slurs” people.

6:30: Paul defends the newsletters, written under his name in the 1990s, that included racial inflammatory rhetoric. He praises Martin Luther King Jr., saying he admired him because he believed in “peaceful resistence,” while pointing out the unfair enforcement of drug laws because minorities are disproportionately targeted.

6:38: “George, this is an unusual topic you are raising,” in response to a question whether states have a right to ban contreception. Romney gets laughs when he turns to Paul and says, “why don’t we ask the constitutionalist.” He says he doesn’t know, but interestingly reminds that he favors a constitutional ban on same-sex marriage. He thinks the question is silly because no one has proposed it. “Contreception, it is working just fine. Just leave it alone.” That gets laughs. By making a joke out of it, even as he got a bit flustered, Romney seems to have survived a question that really could have tripped him up. Several tweeters have pointed out that Romney supported Mississippi’s “personhood” amendment, which would have given the state the ability to ban some forms of contreception. It failed to pass.

6:45: Same-sex marriage: Gingrich reiterates his opposition, but Huntsman says “I don’t think my marriage is at all threatened by civil unions.” He’s separating himself from other candidates, even though he stops short of endorsing same-sex marriage. But he is undermining an argument made by many social conservatives.

6:47: There is evidence that Santorum’s confrontional encounters with same-sex marriage supporters in New Hampshire may be stalling his rise. But he is not softening his stance, and once again says that if a constitutional amendment is passed banning same-sex marriage, it would invalidate those that exist.

Gingrich tries to stop all of the concentration on same-sex marriage by attacking the liberal media, and wonders why no one is asking about “anti-Christian bigotry,” like Catholic groups losing funding because they do not provide adoption services for same-sex couples. “The bigotry goes both ways,” Gingrich says.

What is growing apparent is that opposition to same-sex marriage is not the slam dunk that it once was, even in a Republican primary. Increasingly, opponents have been casting the issue as one of religious freedom, rather than argue that it is a threat to the sanctity of marriage. Obviously, the latter argument is a hot potato for Gingrich.

7:02: Sending troops in to fight: Romney says it is a “very high hurdle.” He’s critical of Obama, but it is unclear how that squares with his criticism of Obama on the withdrawal from Iraq or Romney’s continued support for action in Afghanistan. Paul, however, reiterates his point that Iraq and Afghanistan were undeclared wars, and warns about the drumbeat to go into Iran. he also slams the sanctions against Iran. “The policy sends Iran right into the hands of the Chinese,” he says. It’s amazing to imagine what this or any of the debates would be like without Paul to identify the huge gulf between him and other candidates on foreign policy.

7:12: Romney calls for improving infrastructure — bridges and roads — which essentially means more spending. But he immediately diverts attention to the private sector, and accuses Obama of trying to create a “social welfare state.”

Gingrich, too, is for infrastructure spending, although he connects an energy independence program with boosting spending on bridges, roads, technology, etc. Huntsman supports reform of the tax code and the proposals of the Simpson-Bowles commission.

Santorum calls for zeroing out the corporate tax on manufacturing. Romney comes back and says that he’d eliminate tax on savings for the middle class.

7:23: The debate is almost 3/4 over, and Mitt Romney is still like a spectator watching the rest of the candidates spar with each other, or, in the case of Huntsman and Perry, just try to get some airtime at all.

7:25: Perry gets applause for his “vision,” while Huntsman points out that he’s the only candidate who has called for an overhaul of all of the tax code loopholes, a much more dramatic overhaul than the rest. Rommey is asked why he doesn’t support such a plan, but he turns his attention to President Obama. It is essentially a short version of his stump speech.

7:32: Romney’s first attack on Jon Huntsman, for working for the Obama administration. But the bigger message is that he’d be more aggressive on trade with China. Huntsman actually speaks some Chinese and says, “He doesn’t know what he’s talking about,” warning that he’s provoke a trade war that would hurt small business. Romney: “We are not going to let them run all over us and steal our jobs.”

Huntsman should have benefited from the attention, but as Larry Sabato tweets, “Uh-oh. Huntsman just reinforced nuts who think he’s Manchurian Candidate. But we all enjoyed his Chinese.”

7:41: That’s it. Few attempts to try to take down Romney. Jake Tapper: “It is almost as if they weren’t aware that Mitt Romney were the front runner.” This was nothing other than a good night for Romney, with little to suggest that there was a significant movement in New Hampshire toward any alternative. If Huntsman and Perry were trying to make a show to stay in the race, they didn’t do it tonight. The stakes couldn’t be any higher, but there’s always tomorrow.

Greg in Hollywood has a roundup of celebrity tweets about the debate here.