GOFFSTOWN, N.H. — Mitt Romney gave supporters here advice today on how to defend his candidacy against critics who call him a flip-flopper, spinning the issue into a sales pitch for his private sector experience.

“How do I fight these people?” a Romney supporter asked the former Massachusetts governor.

“Let me give you some brass knuckles, that will help,” Romney quipped during his town hall at the New Hampshire Institute of Politics at St. Anselm College.

Romney added that he doesn’t “whine” about being called a flip-flopper — New Hampshire Democrats mounted a stunt involving flip-flop shoes to welcome the Republican to the Granite State — because he knows being in politics can get “pretty rough and tumble.”

Then he offered what’s become a standard line of defense when he is charged with being on both sides of President Barack Obama’s health care law, gay rights and economic issues.

“In the private sector, if you don’t change your view when the facts change, you get fired for being stubborn and stupid,” Romney said. Then he outlined his résumé and said his business experience makes him uniquely qualified to be president.

Several voters said they found the Republican, who leads New Hampshire polls, to be more authentic this time around than he seemed during his unsuccessful 2008 White House bid.

State Rep. Jack Flanagan stood among the crowd to tell Romney, “You’re a better candidate now than you were four years ago.”

Retired postal clerk Edward Smith of Goffstown told Roll Call he was impressed by Romney’s performance and plans to back him a second time.

“It seems like running nationally you learn a lot, so he’s had a lot of time to think about it. The four years has helped a lot,” Smith said. “Romney knows what he’s talking about.”

Romney told the crowd it’s “a good thing” that New Hampshire has the first primary and that voters “poke at me and ask tough questions.”

Earlier today, Florida and several states were jostling to move their primary contests earlier in 2012. Romney told reporters after his town hall that Iowa and New Hampshire would retain their first-in-the-nation statuses.

He dodged a question about whether he would avoid campaigning in Florida should the state move its contest earlier. “We’re ready whenever the process begins” was all he would say.

Romney also wouldn’t take a reporter’s bait on the potential candidacy of New Jersey Gov. Chris Christie, only saying the Republican is “a great guy and a colorful character.”

“It would be fun if he got in,” Romney said.

Without naming his chief opponent, Rick Perry, Romney offered a veiled jab about the Texas governor allowing in-state tuition for illegal immigrants.

“I’d rather give it to you, I’d rather forgive your loans than have our taxpayers paying for people here illegally,” Romney said, pointing to a 2008 college graduate in the crowd who had told him she is being crushed by $45,000 in student loans.

Romney mocked Obama’s chief political adviser, David Axelrod, who spoke at the New Hampshire Institute of Politics on Tuesday. Axelrod had said the re-election campaign “is going to be a titanic struggle, but I firmly believe we’re on the right side of the struggle.”

“I’m not sure he knows what that word means. I’m not sure he saw the movie,” Romney said today.

Romney spoke with a national debt ticker as his backdrop, alongside his fiscal plan: cut, cap and balance the budget, reform entitlements, and reduce and restructure government.

He outlined a few policy positions and floated ideas on a state-based immigration policy and curbing higher education costs for veterans. Romney said he had been thinking about the debate question that candidate Herman Cain fielded last week: Which government agency would you eliminate if you became president? He said he would opt to “cut dramatically” or combine agencies including the Department of Education, the Commerce Department and the Environmental Protection Agency.

“The list would be very, very long indeed of those that need to be dramatically shrunk. … Government has become too big, and the EPA is one of the worst examples of that,” he said.

After a question about climate change, Romney said that although there is some “to and fro” about the scientific consensus, he would acknowledge the planet is “probably getting warmer.” But he added that he is “not willing to spend trillions and trillions of dollars to go after something we may not be the major contributor to.”

Romney seemed to speak with ease to the capacity crowd, joking with a child who asked about taxes on baby sitters that if she was earning less than $50,000 per year, she was probably fine. Another youngster asked Romney what he would tell her classmates to encourage them to become politicians.

The crowd roared with laughter when he deadpanned: “Nothing, don’t do it, run as far as you can.”