Last year's frontrunners are this year's longshots, and vice-versa.
It would have seemed inconceivable until recently that New Jersey Gov. Chris Christie might now be forced to defend his viability as a 2016 presidential candidate.
Polls had him in first place among Republicans. He was lavished with love by establishment voices in Republican-friendly media. And he had a reputation as a dynamo in his own state, fresh off a re-election landslide.
Yet there he was, being challenged in a roomful of conservatives to explain why he still has any chance.
"Now you're down near the bottom. Jeb Bush, Scott Walker... Ben Carson... are ahead of you," right-wing radio host Laura Ingraham asked him during a question-and-answer session in front of more than 1,000 people at the annual Conservative Political Action Conference.
"That's pretty low... How do you overcome that deficit? It's a pretty big deficit."
To which the New Jersey governor shot back: "Is the election next week?" He added, "I'm not worried what the polls say 21 months before we're gonna elect a president of the United States."
He noted that at the same stage in the 2008 election cycle the political world was predicting a presidential showdown between Rudy Giuliani and Hillary Clinton — not John McCain and Barack Obama.
He has a point. And it's especially true, this time, on the Republican side.
The presidential wheel of fortune could settle on any one of a number of potential Republican candidates. Whereas, among Democrats, Hillary Clinton is considered such a shoo-in that she hasn't even begun campaigning and her potential supporters are already fighting for spots in her organization.
Christie's career prospects were similarly sunny a year ago.
At the start of 2014, he led among Republicans according to an average of polls compiled by the website Real Clear Politics. Rand Paul, the Kentucky doctor turned libertarian senator, was in second place.
His problems began with what appeared to be the politically motivated shutdown of a bridge by his staff. Add in some struggles with reforming state pensions; New Jersey's eight credit downgrades; a European trip marked by ill-received comments about choice in vaccination; and reports about wealthy travel subsidized by taxpayers, businesses and Jordan's King Abdullah, and you wind up with a column in the New York Times this week that reaches a most dire conclusion: "Chris Christie is political toast... Christie is now about as serious a presidential prospect as Donald Trump."
Then it was Paul flying high for much of the year.
What happened to him, apparently, was ISIL.
The focus of U.S. politics shifted from economic issues, where he's a hawkish Republican, to military issues, where he's more in tune with dovish Democrats. His poll numbers dipped around the time Islamist rebels first took over northern Iraq, and then dipped again after the U.S. began airstrikes.
He's now treated by many as a second-tier candidate, far behind in Iowa, and not leading in any of the key primary states.
But the conference illustrated the fluidity of the 2016 picture.
Paul had a good week.
He won a straw poll of CPAC attendees, albeit by a much smaller margin than 2014. And he stood his ground on tough terrain. Most speeches at CPAC delivered applause lines on an identical series of themes — Obama's weak, the economy's soft, Clinton's tired, national education standards are bad, and presidential immigration changes are unconstitutional.
Paul challenged the party orthodoxy.
On foreign affairs, he said American military meddling had made the world more dangerous, in places like Libya and the Middle East, and he urged a more cautious course.
"At home conservatives understand that the government is the problem, not the solution. But as conservatives we should not succumb to the notion that a government inept at home will somehow become successful abroad," Paul said.
"That a government that can't even deliver the mail will somehow be able to create nations abroad."
He then urged his party to care as much about other parts of the U.S. Constitution as it does about the Second Amendment's gun rights.
What about the Sixth Amendment's right to a speedy trial, or the Fourth Amendment's unlawful search and seizure? "The phone records of law-abiding citizens are none of (government's) damned business," Paul said. "We must protect ourselves from jihadists without losing who we are in the process."
Some of his supporters organized a walkout during a speech by one of the new frontrunners, Bush. The brother and son to two former presidents is considered the favoured candidate of the party's establishment wing.
But hostility to Bush was evident from the boos and heckles he received, not to mention his fifth-place showing in the straw poll.
Even the rising star among the grassroots had some trouble last week. Scott Walker, the union-busting Wisconsin governor, entered the convention riding a wave of buzz and strong poll numbers.
But the biggest buzz he created at the conference was when he was asked why he was qualified to fight terrorism. His answer? He'd already stared down Wisconsin unions.
"If I can take on 100,000 protesters, I can do the same across the globe," Walker said. And that drew fire from Rick Perry, the Texas ex-governor who would be delighted to take his place on that wheel of presidential fortune.