But two weeks ahead of the final Republican debate of the year and two months before the first votes of the primary season are cast, Trump's rambunctious presidential campaign is thriving.

Controversies and outrages that would topple ordinary political candidates leave Trump without a scratch. In fact, the Republican front-runner seems to be deliberately stoking the outrage among his supporters that sustains his campaign — whether it's by embracing unsubstantiated claims that thousands of Muslims in New Jersey cheered the fiery collapse of the World Trade Center on September 11, 2001, or by advancing his disputed charge that the Obama administration wants to ship 200,000 Syrian refugees to the United States who could include terrorists.

In a season of political anger, a pundit-confounding, anti-establishment wave has lifted political newcomers like Trump and left conventional candidates like Jeb Bush and John Kasich floundering. And, in the absence of a unified GOP establishment opposition, the fractured, bloated GOP field gives Trump a real chance of capturing early voting contests that are the gateway to a sustained bid for the nomination.

'Surprise people'

"I think he is going to continue to surprise people," said Bill Miller, a veteran Republican political consultant from Texas.

"The question about Trump is: Can he go the distance? We will see. But I would not sell him short," said Miller, who believes the tumultuous Republican race could go all the way to the party's national convention in Cleveland next July.

Should Trump manage to rack up multiple primary wins and hundreds of delegates, the 2016 election would recast long-held conventions of the rhythms of presidential nominating contests and could even reshape American politics itself.

Pundits, GOP party officials and campaign reporters have for months expected the surge of the anti-politicians to crest and for traditional hopefuls to rise to the top of the polls, a pattern familiar from previous campaigns.

Photos: Who's running for president? Photos: Who's running for president? Ted Cruz, Donald Trump, John Kasich, Hillary Clinton and Bernie Sanders, Hide Caption 1 of 6 Photos: Who's running for president?



"So, ladies and gentlemen, I am officially running for president of the United States, and we are going to make our country great again," Trump told the crowd at his announcement. Businessman Donald Trump announced June 16 at his Trump Tower in New York City that he is seeking the Republican presidential nomination. This ends more than two decades of flirting with the idea of running for the White House."So, ladies and gentlemen, I am officially running for president of the United States, and we are going to make our country great again," Trump told the crowd at his announcement. Hide Caption 2 of 6 Photos: Who's running for president?



"These are all of our stories," Cruz told the audience at Liberty University in Virginia. "These are who we are as Americans. And yet for so many Americans, the promise of America seems more and more distant." Sen. Ted Cruz of Texas has made a name for himself in the Senate, solidifying his brand as a conservative firebrand willing to take on the GOP's establishment. He announced he was seeking the Republican presidential nomination in a speech on March 23."These are all of our stories," Cruz told the audience at Liberty University in Virginia. "These are who we are as Americans. And yet for so many Americans, the promise of America seems more and more distant." Hide Caption 3 of 6 Photos: Who's running for president? Ohio Gov. John Kasich joined the Republican field July 21 as he formally announced his White House bid.



"I am here to ask you for your prayers, for your support ... because I have decided to run for president of the United States," Kasich told his kickoff rally at the Ohio State University. Hide Caption 4 of 6 Photos: Who's running for president?



"Everyday Americans need a champion, and I want to be that champion -- so you can do more than just get by -- you can get ahead. And stay ahead," she said in her announcement video. "Because when families are strong, America is strong. So I'm hitting the road to earn your vote, because it's your time. And I hope you'll join me on this journey." Hillary Clinton launched her presidential bid on April 12 through a video message on social media. The former first lady, senator and secretary of state is considered the front-runner among possible Democratic candidates."Everyday Americans need a champion, and I want to be that champion -- so you can do more than just get by -- you can get ahead. And stay ahead," she said in her announcement video. "Because when families are strong, America is strong. So I'm hitting the road to earn your vote, because it's your time. And I hope you'll join me on this journey." Hide Caption 5 of 6 Photos: Who's running for president?



"This great nation and its government belong to all of the people and not to a handful of billionaires, their super PACs and their lobbyists," Sanders said at a rally in Vermont on May 26. Sen. Bernie Sanders , an independent from Vermont who caucuses with Democrats, announced his run in an email to supporters on April 30. He has said the United States needs a "political revolution" of working-class Americans to take back control of the government from billionaires."This great nation and its government belong to all of the people and not to a handful of billionaires, their super PACs and their lobbyists," Sanders said at a rally in Vermont on May 26. Hide Caption 6 of 6

But surveys have repeatedly shown roughly half the Republican primary electorate spurning candidates preferred by party elites in favor of Trump, retired pediatric neurosurgeon Ben Carson and, fleetingly, businesswoman Carly Fiorina -- driven by visceral hostility to Washington, establishment GOP leaders and even the idea of governance itself.

Trump in particular has demonstrated remarkable staying power. In the latest national poll of the Republican race, by ABC News and the Washington Post, he led with 32%, followed by Carson at 22%.

Still, as the first-in-the-nation caucuses and primaries loom closer — and as more voters tune in — the challenges and pitfalls facing Trump and Carson intensify.

To start, polling this far out is still not a foolproof predictor of who will turn out to vote and who those voters will choose.

"I don't think any political scientist would have thought in November that Trump would still be ahead in the polls," said Jennifer Lawless, a political scientist at American University.

"That said, most of us would say it's still pretty early," she continued. "Until those first votes are counted, we don't know what his ground game is."

Real test

While Trump has dominated polls and media coverage of the race for months, the only real test of whether a political neophyte can build the kind of precinct-by-precinct machine normally required to win in Iowa and New Hampshire is on voting day itself.

Many political scientists, who base their analysis on long-term trends and data rather than daily ups and downs, say it is too soon to determine whether Trump or Carson will open a new chapter of campaign lore or whether political precedent built up over multiple elections, in which an establishment front-runner emerges and outsiders drop off, will prevail.

"I am uncertain that we are yet at a place where we should say the pattern of history is about to be broken," said John Sides, a George Washington University professor. "I am a little bit cautious about saying this is the year of the outsider and everything we thought we knew about primaries has to go out of the window because this time is different."

Still, Trump has already won a significant victory -- he has dominated a campaign in which many pundits expected him to be merely a fast-rising, fast-fading sideshow.

Showing a mastery of the media, flouting political correctness and identifying and then harnessing outrage seething in the Republican base more effectively than any other candidate, Trump has led national polls since July.

In the process, his jeremiads on immigration and Syrian refugees have dragged his rivals further right than they might have wished to go. And he's proven he is no shooting-star outsider like Michele Bachmann or Herman Cain in 2012.

Though Carson's ascent has slowed in recent weeks amid questions about his biography and foreign policy credentials, Trump remains dominant. In first-in-the-nation Iowa, for instance, Trump leads Carson, and their combined slice of the vote is between 49% and 45% in most polls.

'Silent majority'

And there are signs that what Trump calls his "silent majority" -- which many others consider an angry, vocal block of the Republican electorate -- is standing firm behind him.

A CNN/ORC Poll published on November 6, for instance, found that among Iowans who have definitely decided whom to support in that state's caucuses, Trump led with 39%, ahead of Carson at 22%, Texas Sen. Ted Cruz at 14% and Florida Sen. Marco Rubio at 8%.

But despite Trump's poll numbers -- which often are his focus for a large portion of his stump speech -- elections are not won in the calendar year before anyone votes. And his campaign will soon face real tests.

There is, for example, strong evidence that despite the huge viewing figures piled up by televised presidential debates and a rollicking Republican campaign, many GOP voters have yet to make up their minds. That means that polling numbers two months out from the early state voting contests may not be as solid as they appear.

A Monmouth University Iowa Poll in late October found that 19% of Republican voters were completely set on their choice of candidate. Monmouth found a similar story in South Carolina this month, where 17% of likely primary voters in that early state were settled on their pick. Another 39% said they had a strong preference but were willing to look at other candidates.

The nominating process, particularly in caucus states like Iowa, relies on a high level of organization and self-motivation of voters to participate on election night. Some observers question whether those attracted by Trump's denunciations of the political establishment and furious at government will ultimately be sufficiently committed to brave chilly winter temperatures to participate in the ritual of voting.

"Trump and Carson are banking on the fact that people who are so turned off by politics are going to rally and get behind them. But political scientists have long known that people who are turned off by politics don't engage (in) the system," said Lawless.

Still, Miller, who believes that ultimately, Rubio may be the best bet to win the Republican nomination, nevertheless argued that "anger is a pretty strong motivator in politics," and that Trump was doing a good job of keeping the pot boiling among his base of supporters.

"I think the most important thing for them is to stay angry. As long they are mad, they will vote."

Another factor helping Trump and Carson so far has been the packed Republican field -- the establishment vote is splintered among candidates like Rubio, Bush, Kasich and New Jersey Gov. Chris Christie -- and no clear front-runner from this group has yet emerged.

More scrutiny

But the newcomer candidates can also expect more scrutiny as the first ballots near.

After the Paris terror attack earlier this month, for example, foreign policy knowledge has become more of an issue -- perhaps putting Carson at a disadvantage. Among his supporters at least, Trump's bombast on national security has been welcomed.

A further challenge for the outsiders lies in expanding their appeal. The polling ceiling that is consistently evident in Trump's performance could become a major detriment.

Though he leads in almost every national and early state poll, it's not often that Trump polls above the low 30% range. With a fragmented field, that's sufficient to keep him at the top of the pack. But that could change if the GOP unites behind "anyone but Trump."

While outsiders Trump and Carson together poll around 50% in most surveys, it's also not clear whether their vote is interchangeable. The support that the pediatric neurosurgeon wins among evangelical voters may not be available to the more raucous Trump. In fact, a recent spike in Iowa polls by Cruz may indicate the Texas senator is already profiting at Carson's expense.

If Trump cannot break out, he would not be the only outsider candidate to discover limited horizons. There is, after all, precedent for angry, populist outsiders doing well in some states and polls but failing to build a true national movement.

In the 1988 Iowa caucuses, television evangelist Pat Robertson polled nearly 25% but came second to an establishment front-runner, Sen. Bob Dole. Eight years later, the elites' choice was Dole again, who just edged out former Reagan aide and conservative commentator Pat Buchanan in Iowa. Buchanan actually won in New Hampshire that year, but Dole captured the nomination. And in 2000, media baron Steve Forbes polled 30% in Iowa -- close to Trump's current ceiling -- but it was the traditional candidate, George W. Bush, who won.

Historic campaigns

Recent history shows no case in which a GOP "outsider" candidate has managed to transform popularity in early states into a formidable and victorious national campaign. Even successful candidates considered outsiders have had traditional credentials.

In 1964, conservative icon Barry Goldwater ran as an outsider and won the nomination against the party establishment -- but like Cruz was already a sitting senator. Ronald Reagan was seen by many conservatives as a rival of the Republican Party bosses, but by the time he won the nomination, he had already won two terms as California governor.

It's also possible that Trump's own behavior could hamper his chances of breaking out. Tactics that make him beloved among his most faithful supporters -- like vows to build a wall on the Mexico border, attacks on the press and his opponents and a volatile campaigning style -- may harm him among a wider electorate.

While his core support has been impervious to slippage after previous controversies, such behavior could complicate Trump's bid to appeal to more moderate primary voters and the broader country should he win the nomination.

In turn, Republican voters may begin to question whether Trump is the GOP candidate with the most potential to beat likely Democratic nominee Hillary Clinton in a year's time.

If he did prevail in the primary process, Trump would present the Republican Party with a dilemma -- whether to accept a potential nominee who many fear could stumble in a general election or to try to install an alternative, perhaps in a coup at the party convention in Cleveland that might enrage the GOP base and tear the party apart.