DeChristopher who was convicted of two felonies for making protest votes during a December 2008 federal oil and gas lease auction with no intention of paying for them says in his letter that Huntsman showed "integrity" as Utah's governor while up against a Legislature "that makes the U.S. House look sane."
"He has guts, which is more than anyone can say for Obama," DeChristopher wrote. "If Huntsman wanted an endorsement from a lefty activist felon in prison, he would have it."
Huntsman has struggled in his White House bid but refused to distance himself from a politically dicey belief that climate change is human-caused and needs to be addressed.
Huntsman's campaign acknowledged DeChristopher's endorsement but quickly steered the conversation back to the candidate's economic plans.
"We hope he has relatives in New Hampshire who can support the candidate who has offered the most conservative, pro-growth jobs plan in the field," said Huntsman spokesman Tim Miller.
DeChristopher's support isn't likely to ding Huntsman's hopes in New Hampshire, which holds the first primary contest in the nation. And with economics and jobs as the key issue, environmental causes appear to be on voters' back burner.
"I don't think there are 100 GOP primary voters who vote on climate issues, so I don't think it has any effect," says Fergus Cullen, a former New Hampshire Republican chairman.
But Huntsman could draw some independents who like his approach to climate change compared to his rivals' efforts to disavow humans' role in the problem.
Brigham Young University geoscientist Barry Bickmore, a Republican who speaks out on the importance of dealing with climate change, said he also would back Huntsman in sticking with the science.
Like DeChristopher, Bickmore said he would like to put climate change at the top of the agenda for more voters.
But the GOP, with candidates like Mitt Romney and Newt Gingrich backing away from the issue, it appears as though the GOP is becoming an anti-science party and imperiling its own future as a result, Bickmore said.
"If the Republicans don't get together and stop pretending the problem doesn't exits," he said, "in a couple of decades it will become so apparent that we were in denial about this that the party will be gutted, we'll be turned out on our ear."
Huntsman has warned much the same thing in recent debates.
Randy Simmons, the Charles G. Koch Professor of Political Economy at Utah State University, agreed that Huntsman's stance on climate change might position him to build support among a broader philosophical spectrum possibly beyond the 2012 election.
"If he can pick up votes from lonely, left-leaning voters, he could do reasonably well in a general election," said Simmons, a libertarian who said his comments were his own and not the views of the university. "The trick is for him to get through the primary, and I don't think he can do that."
DeChristopher has no illusions about that either, writing in part, "Of course Huntsman can't win his party's batshit crazy primary."
Link to Tim DeChristopher's letter