The still-crowded field for the Republican presidential nomination will be sorely tested over the next 40 days, consigning some to the proverbial political wilderness while a handful will emerge as credible candidates.
"If I don't win, I will consider it a total and complete waste of time," said bombastic billionaire Donald Trump, who has enraged many while delighting his legion of devotees with a steady stream of sweepingly savage attacks on women, Mexicans, Muslims and anyone else who dares to disagree with him.
But Mr. Trump's brash, self-aggrandizing style – to swoop in aboard his black-painted, private Boeing 757 replete with gold-plated seatbelt buckles, lead a rousing rally of cheering supporters and then bask in the spotlight of unmatched television coverage – is ill-suited to the hard slogging required to succeed in the Iowa caucuses and the New Hampshire primary.
Those small, overwhelmingly white, completely unrepresentative and quite different states are the sites for the first two – and disproportionately important – dates on the long calendar of voting that will select the Republican Party's nominee.
Mr. Trump, who for months has held a commanding lead over his rivals in national polls, has slipped in Iowa. Traipsing around the state and dealing with interminable town-hall meetings is the long-established path to success in the caucuses, where dedicated party members will gather on Feb. 1 for a long winter evening of talk in community halls and school gyms before picking their favourite.
Mr. Trump is already discounting the seriousness of a defeat in Iowa, where recent polls show him trailing Texas Senator Ted Cruz, who has devoted much time and effort in the state. "If I come in second by two points, they'll say, 'Ooh, this is a terrible defeat,'" he said, lampooning the pundits who have been predicting that the former reality TV show star will eventually flame out.
He promises a big media buy to stem the slide in Iowa and avoid one in other early voting states. "I'll be spending a minimum of $2-million a week … on big ads in Iowa, New Hampshire, South Carolina," he said this week.
That too is a departure for Mr. Trump, who has mostly boasted about how his self-financed campaign has cost very little while attracting enormous media attention. "I have spent almost nothing on my run for president and am in 1st place," Mr. Trump gleefully tweeted.
"Jeb Bush has spent $59-million & [is] done," he added, referring to the former Florida governor whom many pundits expected to be the dynastic front-runner.
Mr. Trump has made a habit of mocking Mr. Bush, who is desperately trying to kick-start his faltering campaign. This week, the son and brother of former presidents ordered scores of Miami-based staff to leave the office and hit the road in Iowa and New Hampshire.
Losing in Iowa might be survivable for Mr. Bush (his father lost there and his brother won), but a poor showing in both the first two primary states would probably doom the chance of a third Bush in the White House.
Meanwhile, Mr. Cruz, a Tea Party favourite and Harvard-trained lawyer, is picking up support from those on the right wing of the party who regard Mr. Trump as too outrageous or perhaps just unelectable.
He has been stumping Iowa the old-fashioned way. Next week, he will spend six days on a bus tour with 28 stops in places like Dr. Thomas Gleason's Airplane Hangar in Webster and the Praise Community Church in Mason City.
Mr. Trump's disdain for that type of painstakingly personal politics was evident when he made a rare town-hall appearance in New Hampshire. "I don't normally do stops like this," he said during a session that lasted less than 15 minutes.
Others, such as New Jersey Governor Chris Christie, have spent countless hours in New Hampshire. Although Mr. Christie barely registers in national polls, he is currently tied for third with Mr. Cruz in New Hampshire – still behind Mr. Trump and Florida Senator Marco Rubio but well ahead of most of the pack.
For some Republican hopefuls, such as retired neurosurgeon Ben Carson, whose campaign is seemingly in free fall after briefly challenging Mr. Trump for the lead a few weeks ago, staying competitive will require a top-three showing in Iowa or New Hampshire.
Similarly, Ohio Governor John Kasich, Kentucky Senator Rand Paul and former Hewlett-Packard chief executive officer Carly Fiorina – all struggling to emerge from the dwindling number of also-rans – must do well in at least one of the states.
The next televised Republican debate, on Jan. 14, will further divide the field. Only six candidates will be included in the main debate sponsored by Fox Business Network based on a combination of national polls and polls in Iowa and New Hampshire.
Currently, Mr. Trump, Mr. Cruz, Mr. Rubio, Mr. Carson, Mr. Bush and Mr. Christie make the cut. By the time the New Hampshire primary votes are counted on Feb. 9, the number of viable Republican candidates headed for South Carolina's primary 11 days later will be smaller still.