Republican presidential candidate Donald Trump speaks during a campaign stop before next months earliest in the nation presidential primary, Monday, Jan. 11, 2016, in Windham, N.H. AP FILE PHOTO
WASHINGTON, United States鈥擯oll-leading showman Donald Trump faces the first test of his meteoric political career on February 1, when voting to elect a new US president begins.
In just over a week, around 120,000 Iowa Republicans will have the first word on their party鈥檚 White House nominee.
READ: Candidates swarm Iowa, first big test in US election marathon
They are telling pollsters Trump is their man.
During a six-month campaign, the 69-year-old tycoon has slapped aside conventional political wisdom, blustering and brawling his way to a lead over his rivals.
鈥淭rumpism鈥� is 鈥渁 toxic mix of demagoguery and nonsense,鈥� said former Texas governor Rick Perry, before crashing out of the Republican race as one of the billionaire鈥檚 first political fatalities.
Most Americans have looked on with bewilderment as Trump has insulted Mexicans, Muslims and most of the Republican establishment.
READ: Trump wants Muslims totally barred entry to US
But Trump鈥檚 mix of theatrics, populism and refusal to do politics-as-usual has proven a potent brew.
The latest national polls show he has a 16-point lead over his nearest rival, Texas Senator Ted Cruz.
Grassroots white Republicans appear intoxicated by a candidate who exudes confidence, shuns political correctness and challenges professional politicians they see as too timid, and as ideologically suspect.
He appeals, in the words of David Frum鈥攁 veteran of George W. Bush鈥檚 White House鈥攖o 鈥減eople who are irked when asked to press 1 for English.鈥�
Trump has also enthralled ratings-chasing television executives who are delighted to broadcast his rallies live鈥攁s long as he delivers eyeballs.
According to statistics from the GDELT Project, Trump receives roughly as much television coverage as all other Republican and Democratic candidates combined.
That leaves those trailing in his wake unable to gain momentum, while saving Trump tens of millions of dollars on paid advertising.
The mogul鈥檚 improbable political journey was summed up by respected University of Virginia political analysts Larry Sabato, Kyle Kondik and Geoffrey Skelley.
鈥淭he political world has moved from disbelieving that he would even follow through and become a candidate, to expecting him to wither on the vine as more conventional choices gained steam, to accepting his nomination as a distinct possibility, to speculating that he will go all the way and defeat Hillary Clinton in November,鈥� they wrote.
But come February 1, none of the polls, none of the punditry and none of the noise matter.
鈥楤ored with winning鈥�
The first-in-the-nation ballot will be the first real test of whether Trump can turn celebrity into a political movement.
Doubts remain about whether he has the campaign structure in place to turn fans into voters.
If he can, it would be a political earthquake in the Republican party.
For much of the last eight years, establishment Republicans and the party base have papered over vast differences with similar tough sounding rhetoric and a mutual disdain for President Barack Obama.
Trump has fueled that long-muted battle for the soul of the party.
Many moderate Republicans view Trump as an unmitigated disaster: alienating electorally vital minority groups and likely handing the Democrats a third term in the White House.
For months, their mantra has been 鈥渓et me know when he wins some delegates.鈥�
But there are increasing signs of panic.
The National Review, a torchbearer for conservative Republicans, devoted a whole issue to attacking Trump, calling him 鈥渁 philosophically unmoored political opportunist鈥� who would trash ideological consensus inside the party.
In the face of a Trump victory in Iowa, cooler heads may point out that the state is a notoriously bad indicator of who will become the party nominee, never mind president.
In the last two cycles, Iowa Republicans have backed Rick Santorum and Mike Huckabee, who did not get within shouting distance of the nomination.
If Trump loses, it will be a serious test for a candidate who promised 鈥渨e will have so much winning if I get elected, that you may get bored with winning.鈥�
So far Trump has met each dip in the polls with a fresh airtime-earning controversy.
Whatever happens in Iowa, expect more controversy ahead.