With his bid to become president as a Republican seeming to be more of a long shot each day, Jon Huntsman isn't completely closing the door on an independent run for president.

Still, Huntsman, who is close to last place in polls across the country, says he's been a "lifelong Republican" and wants to be the party's nominee to take on President Obama (who was his boss when Huntsman was U.S. Ambassador to China).

Huntsman told reporters at the National Press Club on Thursday that he plans on winning the GOP nomination, and he brushed aside the idea of running in a third party.

"We're going to finish strong, and there's no need to consider that given where we're going in New Hampshire, which is straight up," he said.

Asked by ABC News if that meant he's ruled out running as an independent, Huntsman only replied, "It means I'm running as a Republican and I have nothing to fear."

His speech at the Press Club was intended as a closing argument, with scathing indictments not only of President Obama, but of the Republican frontrunners, former House Speaker Newt Gingrich and former Massachusetts Gov. Mitt Romney.

Huntsman accused President Obama of squandering the trust of the American people and said Gingrich and Romney "offer no better."

"Governor Romney will say anything to earn the voters trust. We are in this mess because there are already enough people in Washington who make a career out of telling people what they want to hear. Newt Gingrich is a product of that same Washington, who participated in the excesses of our broken and polarized political system," he said.

After his speech, Huntsman refused to offer a number when he was asked how well he expects to do in New Hampshire's primary, on Jan. 10. "I want to come from behind," he said outside the press club. "I'm the underdog."