Republican presidential candidates led by frontrunner Mitt Romney used their first big televised debate to lash out at President Barack Obama -- but not each other. The debate in Manchester, New Hampshire, late Monday did little to define differences between the seven candidates in the unwieldy Republican line-up as White House hopefuls reserved their venom for Obama on the economy and foreign policy. The civil exchanges left Romney, who has a slight, but consistent lead in the polls, still looking like the man to beat for the nomination. Standing behind the center podium in CNN's ultra modern studio, the carefully combed Romney looked suitably presidential as he led the charge against Obama. "Any one of the people on this stage would be a better president than President Obama," Romney said. "Why isn't the president leading? He isn't balancing our budget and he isn't leading on jobs. He's failed the American people... And that's why he's not going to be reelected." Michele Bachmann, a congresswoman and leading light of the staunchly conservative Tea Party movement, momentarily upstaged the other six when she used her opening comments to announce that she had just formally registered her candidacy. Bachmann, the only woman on the stage, elegant in a pearl necklace and pearl earrings, pulled her punches when opportunities came to attack Romney, but she almost shouted during assaults on Obama. "President Obama has failed his leadership," she charged. Newt Gingrich, a veteran Republican who was speaker of the House of Representatives in the 1990s, piled in to attack "the Obama depression." The presidential election is not until November 2012. But candidates were using this event -- the first of many over the coming months -- to solidify their sometimes poor name recognition across the country and position themselves for a grueling campaign. New Hampshire is one of the first states to hold a Republican primary election in February and results there can be crucial to a candidate's momentum heading into follow-up primaries across the country and eventually to the party nomination. For Romney, already well known as a former Massachusetts governor and failed 2008 presidential candidate, the night required avoiding slip-ups and showing he was above the fray. He managed that when former Minnesota governor Tim Pawlenty refused to press earlier attacks he'd made in the media on Romney's introduction while governor of a universal health care plan in Massachusetts. The plan, which became a model for Obama when the president introduced a similar scheme nationwide, is widely detested among Republicans. Romney took the issue head on and said: "If I am elected president I will repeal Obamacare." On foreign policy, there was little daylight between candidates who accused Obama of failing America's longstanding dominance on the world stage and bungling the bombing of Libya. They all said they favored bringing back troops now fighting in Afghanistan, saying nation-building was not the right US role. "This is the first time we've had a president who doesn't have a foreign policy," Romney said. Ron Paul, the prickly and defiantly unglamorous Libertarian congressman from Texas, drew applause when he said he wouldn't wait for generals to tell him it was OK to withdraw from Afghanistan. "I'm the commander in chief," he thundered. "I'd bring them home as quickly as possible." Also in the debate were former senator Rick Santorum and pizza entrepreneur Herman Cain, who has come from nowhere to generate a surprise buzz this primary season, but failed to stand out especially on Monday. The elephants in the room were Republican heavyweights who have not yet joined the race and in some cases insist they won't -- even if they are seen as having more star power than the current offerings. One is Texas Governor Rick Perry, another New Jersey Governor Chris Christie. Also missing was Sarah Palin, a Tea Party favorite and arguably the best known Republican in the country. The former Alaska governor, who so far has failed to appeal much beyond her wildly passionate core support, is flirting with a presidential run, but has yet to declare. Two new polls put her in second place behind Romney. Another non-participant is Jon Huntsman, who until recently was the US ambassador to China and is now seen as a potential dark horse candidate for the Republican nod. He campaigned last week in New Hampshire and says he could declare within two weeks.