Former Utah Governor Jon Huntsman did not seek the 2012 Republican presidential nomination as a liberal Republican in the tradition of Abraham Lincoln, Teddy Roosevelt or Wendell Willkie. He did not even run as a moderate following in the footsteps of Dwight Eisenhower, Gerald Ford or George Herbert Walker Bush.

Huntsman ran as a conservative, who proudly noted that he attended his first Republican National Convention as a delegate pledged to Ronald Reagan in 1984.

But Huntsman did not run as a rigid ideologue who rejected science, reason and logic—especially on matters so consequential as financial regulation and international relations.

In other words, he positioned himself as what we used to call a “responsible Republican.”

Huntsman finished his campaign with the slogan “Country First”—a pointed rejection of the cut-any-corner, crush-any-foe, win-at-any-cost politics that has come to dominate the discourse at Republican gatherings.

This opting out of extremism prevented Huntsman—who, by virtue of his experience as a governor, a diplomat and a genuine business leader, was widely seen as the strongest Republican contender—from getting into serious competition for the party’s nomination. The best he could muster was third-place finish in historically moderate New Hampshire—winning two delegates there and a third from Texas.

Now, the former governor is something of a man without a party. Or, perhaps, the Republicans are a party without a mainstream.

Mitt Romney

Huntsman has announced that he would not be attending the Republican National Convention, which will be held at the end of next month in Tampa.

Politicians sometimes skip party conventions—quite a few Democrats are opting out of their September gathering in Charlotte. But former presidential candidates rarely if ever skip them. (Even in 1972, when the Democratic Party was tearing itself apart, George Wallace showed up to endorse George McGovern. And John McCain, who had no taste for George W. Bush, still went through the convention motions.) So it is significant that Huntsman is not going to Tampa.

And it is an even more significant that he is spelling out why he is skipping the convention.

Huntsman is pointed in his explanation of why he won’t bother to join in the coronation of the contender—Mitt Romney—to whom he has proffered only the most tepid of endorsements. Romney may come from a liberal Republican family, he may have served as a moderate Republican governor of Massachusetts, but he is presiding over a party that no longer has any room for moderation.

Or, Huntsman suggests, the politics of responsible Republicanism.

“I will not be attending this year’s convention, nor any Republican convention in the future, until the party focuses on a bigger, bolder, more confident future for the United States,” says Huntsman, who argues that Republicans must get far more serious about taking necessary steps to give America “a future based on problem solving, inclusiveness, and a willingness to address the trust deficit, which is every bit as corrosive as our fiscal and economic deficits.”

The “trust deficit” is something Huntsman started talking about toward the end of his campaign for the GOP nod. Frustrated by the failure of his fellow candidates to display even a modicum of political independence and ideological openness, Huntsman complained to me that his party was no longer positioning itself as a source of effective responses to the challenges facing the nation. “It’s all talking points,” he said on the day on the New Hampshire primary. “They don’t even try to answer questions—except, maybe, to attack anyone who doesn’t recite the talking points.”

Two days earlier, that frustration surfaced in the second of a pair of back-to-back debates. Romney had ripped Huntsman for joining a Democratic administration, that of Barack Obama, as ambassador to China.

“There are a lot of people who are tuning in this morning, and I’m sure they’re terribly confused after watching all of this political spin up here. I was criticized last night by Governor Romney for putting my country first,” said Huntsman. “I just want to remind the people here in New Hampshire and throughout the United States that [Romney] criticized me… for serving my country in China. Yes, under a Democrat. Like my two sons are doing in the United States Navy. They’re not asking [what] political affiliation the president is. I want to be very clear with the people here in New Hampshire and this country. I will always put my country first.”

Not that many years ago, in the Republican Party of Bob Dole, or perhaps even of the old John McCain, Huntsman’s statement would have been a powerful comeback. But in the Republican Party of 2012, it fell flat. Huntsman got some scattered applause from newspaper editorial writers and TV pundits, but it was clear he was going nowhere in the race for the nomination—a fact he acknowledged when he quit the contest before the crucial South Carolina primary.

In the months since he exited the race, Huntsman has wrangled with party leaders over the party’s failure to focus on fundamental issues, and its increasing ideological rigidity.

This made the former governor one of the few interesting players in a party that has lost almost all of the fluidity and flexibility that was on display at its conventions of 1964, 1976, 1980 and even 1992. It does not invite or encourage real debate or a real search for solutions—let alone the sort of growth or advancement that Huntsman wants.

And the circumstance is not likely to improve in short order.

So Huntsman is not just skipping this year’s GOP convention—as some Democrats are their own party’s gathering. He says he doesn’t plan on attending “any Republican convention in the future.”

That’s an acknowledgment not just of the degeneration of the Republican Party into a narrow right-wing cabal, but also of the fact that the party’s circumstance is unlikely to improve the foreseeable future.

Huntsman knows what he wants the Republican Party to be. His is a reasonable demand—one that most Americans (Republicans and Democrats) undoubtedly share.

“I encourage a return to the party we have been in the past, from Lincoln right on through to Reagan, that was always willing to put our country before politics,” he says.

Unfortunately, the party of Lincoln and Reagan has no Lincolns or Reagans on its horizon. It does not even have room for old-school conservatives like Jon Huntsman.