Game over.

(Reuters) – Presidential hopeful Mitt Romney broke with Republican orthodoxy on Friday by saying he believes that humans are responsible, at least to some extent, for climate change.

“I believe the world is getting warmer, and I believe that humans have contributed to that,” he told a crowd of about 200 at a town hall meeting in Manchester, New Hampshire.

“It’s important for us to reduce our emissions of pollutants and greenhouse gases that may be significant contributors.”

The former Massachusetts governor fielded questions on topics ranging from the debt ceiling to abortion on his first full day of campaigning for 2012 Republican primary nomination.

Romney leads opinion polls in New Hampshire by a wide margin, and is among the top contenders nationally to win the Republican primary.