The rightward march of the Republican Party is about to face a dash toward the center.
And then it just might get a shove back toward the right.
Jon Huntsman's announcement of a presidential campaign on Tuesday, after months of anticipation and behind-the-scenes preparation, will test the limits of a Republican Party that's been trending more conservative in the tea party era.
Meanwhile, if Texas Gov. Rick Perry joins the presidential fray, he'll do so while urging the party back in the direction of its conservative roots.
"Our loudest opponents on the left are never going to like us, so let's quit trying to curry favor with them," Perry said Saturday at a gathering of conservative activists in New Orleans, in a speech that marked his growing interest in 2012.
Both men have much to prove before they can challenge for the Republican nomination against a field of established Republicans who've been plotting runs for years.
Yet while they would come at the race from very different directions, both Huntsman and Perry could shape a fluid nominating contest where candidates are charting much different paths to the presidency.
First comes Huntsman, whose quirky campaign videos -- featuring a man who isn't Huntsman riding a motocross bike across a desert, and not much else -- only hint at the varied record of the candidate himself.
As a former Utah governor who most recently served as President Obama's ambassador to China, Huntsman will challenge notions about the Republican primary electorate in an era of Democratic ascendance in Washington.
His service to Obama is itself disqualifying to some conservatives. Add to that his past support for cap-and-trade energy legislation, the Democrats' stimulus law, and the concept of an individual mandate for health care, and you've got a confirmed moderate in a Republican Party that's proven hostile to them in recent years.
While he's still a virtual unknown nationally, Huntsman's candidacy seems poised to have its most significant impact on frontrunner Mitt Romney, whose shared Mormon roots, family lineage in politics and political pragmatism are also key to the identity he's presenting to voters.
Both men plan strong plays for New Hampshire, where the lack of a competitive Democratic primary frees the state's large crop of independents to vote in the first-in-the-nation Republican primary.
With his non-confrontational style -- he has vowed to mostly avoid criticizing his rivals, or even the president, by name -- Huntsman presents a particular match-up problem to the president's reelection campaign, since he'll be difficult to paint as an extremist.
That's one reason that the president and his top aides are showering Huntsman with the type of praise they know will only hurt him in the primaries.
"I think he's a very bright, fluent person," David Axelrod, the president's top political adviser, said on CNN today.
As recently as fall 2009, Axelrod said of Huntsman, "He was encouraging on health care. He was encouraging on the whole range of issues. He was a little quizzical about what was going on in his own party. And you got the strong sense that he was going to wait until 2016 for the storm to blow over."
A Huntsman spokesman, Tim Miller, fired back by calling Axelrod's comments "absurd."
"Gov. Huntsman's record on health care and the economy in Utah was the opposite of President Obama's top-heavy, government-centric, failed approach," Miller said. "That is the record he will run on."
For his part, Perry has not been one to want to signal an aversion to the current political climate in his party.
Though he's the longest-serving governor in the nation -- he took over after serving as George W. Bush's lieutenant governor, when Bush became president -- he won a third term last year only after embracing tea party enthusiasm in a hard-fought primary race.
Perry advisers have indicated that he's roughly 50-50 on whether to run. That's a significant change for a man who has previously disavowed interest in a national run.
If he does jump in, Perry would be trying to fill a much different void in the field than Huntsman. He'd be the only southerner among top-tier contenders.
He could answer a yearning for a dynamic and solid conservative, with New Jersey Gov. Chris Christie and Mississippi Gov. Haley Barbour among the long list of non-candidates.
Neither Huntsman nor Perry has so far registered strongly in public-opinion polls. But together they could wind up squeezing from opposite ends a party that's hungry to gain back the White House, in what promises to be a fractious primary season.