Donald Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE may be getting the best gift of all this holiday season, as he enters 2016 firmly on top in the Republican race for the White House.

The GOP presidential hopeful has proved the doubters wrong, solidifying a double-digit lead in national polls while running one of the most unorthodox campaigns in history.

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Former Florida Gov. Jeb Bush (R) — who has seen his support plunge amid Trump’s rise — predicted at a private Dallas fundraiser in mid-November that Trump would falter by the next GOP debate.

“Come December 15, Trump will be in decline,” Bush reportedly said.

But on the eve of Christmas, Trump still tops the Republican field by 17 points, even as Bush lags behind in the single digits.

“He’s obviously been able to defy political gravity for much of this campaign,” GOP strategist Matt Mackowiak said, noting Trump’s advantages of being a celebrity and attracting heavy media coverage.

The latest national polls confirm that Trump’s momentum isn’t slowing down. Within the past week, the real estate mogul:

• topped the field in a post-debate survey from Public Policy Polling, increasing his lead by 8 points;

• bested the second-place finisher by 4 points in a Quinnipiac University poll;

• and opened up a 21-point lead in a CNN/ORC International poll.

Trump frequently boasts about his poll numbers on Twitter, using them to fight back against a media he says is biased against his candidacy.

It is hard to believe I am winning by so much when I am treated so badly by the media. New @CNN Poll amazing in ALL categories. 21 pt. Lead — Donald J. Trump (@realDonaldTrump) December 23, 2015

The poll numbers highlight how Trump has displaced President Obama as the central player on the political stage, with both parties reacting daily to his insults, tweets and attack lines.

His dominance is something few political observers would have predicted back on Jun. 15, when he entered the presidential race with a rambling launch speech that some people were allegedly paid to attend.

But Trump quickly gained momentum during the summer, with tens of thousands of people flocking to his rallies to hear how he planned to “make America great again” by deporting illegal immigrants and taking on China.

And even as he’s fired up crowds, the businessman and former reality television star has courted controversy at every turn, creating a steady stream of conflict that has kept his name in the headlines.

Conventional wisdom held that the political storms generated by Trump — most recently from his call to temporarily ban most Muslims from entering the United States — would be fatal to his candidacy.

Yet six months after his entry in the race, Trump sits atop national polls with 35.1 percent support, according to the latest RealClearPolitics average.

His unwavering dominance has stirred anxiety among establishment Republicans, who fear the businessman would be a disastrous nominee.

But while some in the GOP have spoken out against Trump, it has had little impact.

Trump’s lead in the race has become so entrenched that it has allowed him to turn his attention from rival candidates to Hillary Clinton Hillary Diane Rodham ClintonDemocratic groups using Bloomberg money to launch M in Spanish language ads in Florida The Hill's Campaign Report: Presidential polls tighten weeks out from Election Day More than 50 Latino faith leaders endorse Biden MORE, the front-runner for the Democratic nomination.

Still, there are signs that Trump’s closest GOP rival, Sen. Ted Cruz Rafael (Ted) Edward CruzCruz blocks amended resolution honoring Ginsburg over language about her dying wish Trump argues full Supreme Court needed to settle potential election disputes Press: Notorious RBG vs Notorious GOP MORE (R-Texas), is gaining ground.

Cruz even leads Trump in Iowa, which will hold the first presidential contest of the year, on Feb. 1. A RealClearPolitics average of Iowa GOP polls shows Cruz narrowly edging out Trump by 4 percentage points in the caucus state.

Craig Robin­son, a former polit­ic­al dir­ect­or for the Iowa GOP, said Trump has the ability to turn out the tens of thousands needed to win the caucuses. That grassroots fervor could be tough for Cruz to compete with, he said.

“Voting for Trump is going to be a protest vote just like Ron Paul,” Robinson said.

“Trump could completely underperform or overperform," he continued. “I don’t know if Cruz has anything in their arsenal that can deal with the Trump campaign that is bringing new people to the process.”

But he noted the possibility of a dark-horse candidate emerging in the caucuses, such as New Jersey Gov. Chris Christie or the last two Iowa caucus winners, former Arkansas Gov. Mike Huckabee and former Sen. Rick Santorum (R-Pa.).

Should Trump lose Iowa, he will be counting on the next state in line, New Hampshire, to keep his candidacy on track.

Trump has dominated in polls of New Hampshire for months, even as rival candidates such as Bush and Christie have campaigned heavily there.

In the final stretch before the first ballots are cast, the upcoming GOP debate on Jan. 14 could prove crucial, said Mackowiak, who also writes for The Hill's Contributors blog.

“That debate may impact results in Iowa and New Hampshire and start that narrowing of the field,” Mackowiak said. He said the big question for Trump would be getting his supporters to the polls.

“In a way, he’s playing a short-term game,” Mackowiak said.