The bridge scandal that has engulfed New Jersey Gov. Chris Christie has also brought more disruption to the already-muddled early stages of the Republican Party’s search for a 2016 presidential nominee. Republicans appear headed for the most wide-open and unpredictable nomination campaign in decades.

Their prospective field of candidates is mostly untested on the national stage, and a number of them spent the past year generating questions about their readiness rather than burnishing their credentials. Christie is just the latest.

But that’s not the only reason the coming GOP campaign is likely to be neither tidy nor predictable. A power struggle is underway between the party’s establishment and insurgent wings — the business elite and the populist tea party factions. No one is certain what the balance of power in the party will be when the primaries and caucuses begin.

The GOP’s nomination process threatens to be more disorderly this cycle because customs and traditions that have informally governed it in past years seem to be out the window this time.

For starters, there is no experienced heir apparent with an inside track, no dominant figure who has paid dues over many years. Anyone who doubts that Republicans have been a hierarchical institution need only look back at past nomination contests.

Sen. Marco Rubio (R-Fla.) hopes to reestablish his credentials after running into opposition from the right on immigration reform. (Melina Mara/The Washington Post)

Mitt Romney may not have been the darling of the entire Republican Party when he began his quest for the nomination in 2012, but he was as close as the party had to the kind of next-in-line candidate who had so often prevailed in previous contests. The same held true in 2008 for John McCain, even though many conservatives distrusted him.

George W. Bush, the son of a former president and the consensus choice of his fellow governors, was a predictable and almost certain nominee in 2000 — despite an unexpectedly fierce challenge from McCain. Robert Dole had earned his place as the party’s heir apparent when he won the nomination in 1996. George H.W. Bush’s service as Ronald Reagan’s vice president was enough for him to prevail in a crowded and competitive 1988 nomination battle.

No such scenario exists today.

After his reelection in November, Christie became the closest thing to a genuine 2016 front-runner for the Republican nomination, at least among the party establishment and elite donors. His victory margin in a blue state and his strong numbers in the Hispanic community were interpreted as evidence that he could help Republicans capture territory that has eluded them in the past two presidential campaigns.

Now, he is struggling to prove that the qualities that made him so attractive to so many Republicans — blunt talk and tough leadership — have not created a climate of fear and retribution inside his administration that may have led to the bridge scandal.

Perhaps Christie will reclaim his standing as the darling of the GOP establishment. But even if he gets through this controversy, he will still have to overcome doubts and distrust on the right.

In past campaigns, prior experience running for president often gave candidates a boost. That does not appear to be the case this time.

Texas Gov. Rick Perry and former Pennsylvania senator Rick Santorum, who sought the nomination in 2012 and who might run again, are struggling to be seen as serious competitors in 2016. Mike Huckabee, the former Arkansas governor who ran in 2008 and won a number of contests, will have to convince people that he is serious about doing so in 2016, despite some expressed interest.

Perry had one of the more memorable lines about 2012: “It was the weakest Republican field in history, and they kicked my butt.” As the party looked past Romney’s defeat toward the 2016 campaign, Republicans anticipated a much stronger field. But the past year was not so kind to some of these potentially bright stars.

Sen. Marco Rubio (R-Fla.) was on the cover of Time magazine soon after Romney’s defeat, seen as the party’s savior, the candidate who could appeal to the tea party and the establishment and also win over Hispanic voters.

Today, he is working to reestablish his credentials after a year in which he ran into opposition from the right for supporting comprehensive immigration reform and delivered a State of the Union response that was remembered more for a swig of water than the content of his remarks.

On the day the Christie story exploded last week, Rubio gave a substantive speech on poverty. The Christie controversy knocked him out of the news, but Republicans paying attention concluded that Rubio had had a good day to start the year.

The ebb and flow of events brought attention to other prospective candidates. Sen. Ted Cruz (R-Tex.) became a favorite of tea party activists for his 21-hour marathon on the Senate floor attacking the Affordable Care Act. The subsequent partial shutdown of government that he helped engineer resulted in damage to his party. Whether he is more than the leader of a faction of the GOP is the next chapter.

Sen. Rand Paul (R-Ky.) staged a filibuster to draw attention to President Obama’s drone policy. Paul, who has his eye on 2016, has spent the year trying to win greater acceptance within the party for his libertarian philosophy and to show that he has potentially broader appeal to voters than his father, former representative Ron Paul.

The party has a group of governors with presidential ambitions: Scott Walker of Wisconsin, Bobby Jindal of Louisiana, possibly John Kasich of Ohio and Rick Snyder of Michigan, and perhaps others. Walker, Kasich and Snyder have to get through reelection campaigns this year, and they remain largely unknown nationally. Many have potential, but that potential is unrealized for now.

Jeb Bush, the former Florida governor, intrigues many Republicans and worries some Democrats. Whether he will run is an open question, and whether he can excite his party is another. James Carville, the Democratic strategist, told CNN the other day that Bush could be a beneficiary of Christie’s fall.

Rep. Paul Ryan (R-Wis.), the party’s 2012 vice-presidential nominee, also has people guessing: Does he want to be president or stay in the House? Ryan no doubt elevated himself by producing a bipartisan budget agreement at the end of last year, but that is hardly a definitive development this far away from the real competition.

If the prospective field of candidates leaves so many unanswered questions, so, too, does the Republican Party’s unsettled state. No one can be certain at this point where the center of gravity will be when the candidates begin to announce a year from now.

The tea party flexed its muscles during the government shutdown. The establishment has vowed to fight back. Will 2016 be the year that tea party conservatives finally get a nominee of their liking? If so, will that candidate be acceptable to a general-election audience? A series of Senate primaries pitting tea party candidates against incumbent Republicans will help to clarify the shape and potential outcome of the GOP’s nomination campaign by this time next year, although perhaps not definitively.

What the past 12 months — and now the past few days — have done, mostly, is to make things murkier than ever.