* Obama goes on the offensive in early stages of debate
* Candidates circle, confront each other on stage
* Polls show race deadlocked with three weeks left
By John Whitesides and Samuel P. Jacobs
HEMPSTEAD, N.Y., Oct 16 (Reuters) - U.S. President Barack Obama and Republican rival Mitt Romney clashed repeatedly on jobs and energy in the early stages of their second debate on Tuesday, with Obama moving aggressively to challenge his opponent.
Obama was much sharper and more energetic than in their first encounter two weeks ago, when his listless performance was heavily criticized and gave Romney's campaign a much-needed boost.
He repeatedly accused Romney of misstating his policies as president, and resurrected his charge that the economic proposals put forward by the former private equity executive were designed to protect and bolster the wealthy at the expense of the middle class.
"Governor Romney says he's got a five-point plan. Governor Romney doesn't have a five-point plan, he has a one-point plan. And that plan is to make sure that folks at the top play by a different set of rules," he said.
Romney accused his rival of overseeing a stagnant economy. "The middle class has been crushed over the last four years and jobs have been too scarce," the former Massachusetts governor said.
"I know what it takes to get this economy going," he said. "I know what it takes to create good jobs again."
The debate at Hofstra University in Hempstead, N.Y., was in a more intimate town-hall format, in which more than 80 undecided local voters from New York state's Nassau County asked questions.
Both candidates were able to roam the stage to talk directly to the questioners, and at times they circled each other warily like prize fighters.
Romney approached Obama at one point to ask repeatedly if licenses and permits for energy drilling on federal land had been reduced during his administration.
Romney's strong performance in the first debate helped him reverse his slide in the polls, and recent surveys have put the race for the White House at a virtual dead heat just three weeks ahead of the Nov. 6 election.
Obama seems to have stopped the slide in polls after the last debate. In a Reuters/Ipsos daily tracking poll on Tuesday, he gained a bit more ground on Romney for the third straight day and led 46 percent to 43 percent. But a Gallup/USA Today poll showed Romney ahead by 4 percentage points in the 12 most contested states.
Obama rejected the notion that Romney was more supportive of finding more energy sources like coal and natural gas.
" When you were governor of Massachusetts, you stood in front of a coal plant and pointed at it and said this plant kills and took great pride in shouting it down. And now suddenly, you're a big champion of coal," Obama said.
Romney, a wealthy former private equity executive often accused of failing to connect with ordinary people, stayed on the offensive but frequently asked the moderator for more time to answer Obama.