DES MOINES, Iowa - The US presidential race looked suddenly wide open Tuesday after frontrunners Donald Trump and Hillary Clinton suffered chastening evenings in Iowa, the first step on the long road to the White House.

It was a particularly humbling experience for Trump, who cut a forlorn figure after Republican arch-rival Ted Cruz streaked to victory in the Iowa caucuses, staking his claim as the new standard bearer for the conservative camp going on to New Hampshire. 

And if Clinton was in any doubt before Iowa, the former secretary of state now knows she has a real fight on her hands in the form of Bernie Sanders, as final results released Tuesday showed her only seeing off the self-proclaimed democratic socialist by the thinnest of margins.

The months-long presidential contest now kicks into high gear, with Democratic and Republican debates this week building up to next Tuesday's New Hampshire primaries.

Trump, the billionaire real estate mogul and reality television star whose populist campaign turned conventional politics -- and wisdom -- on its head, also now faces a second genuine threat: from Marco Rubio, who chalked up more than 23 percent to Trump's 24.3 percent in the Iowa caucuses.

Surging past expectations, Cruz claimed victory with 27.7 percent of the vote, having invested heavily in campaigning in the deeply conservative state to outmaneuver his many rivals.

While Cruz can hope to build on his momentum in New Hampshire, Sanders returns to what can safely be described as his home turf, with the potential to land a hammer blow against Clinton and her dreams to be America's first female commander-in-chief.

The former first lady hit the ground running at a rally in the state Tuesday, claiming victory even before the release of final Iowa results giving her 49.8 percent, against 49.6 percent for the Vermont senator, her sole remaining rival for the Democratic nomination.

"I am so thrilled that I'm coming to New Hampshire after winning Iowa!" she said to cheers from the crowd. "I can tell you -- I've won and I've lost there. It's a lot better to win!"

But Clinton also acknowledged, later on CNN, that the 74-year-old Sanders has struck a chord with young Americans on the left with his calls for "political revolution."

"I'm going to have some work to do to reach out to young voters -- maybe first-time voters who have to make a tough decision as they evaluate who should be our president, our commander-in-chief. I intend to do that," Clinton said.

Party chair Andy McGuire called the final results "the closest in Iowa Democratic caucus history," with several precincts so close they were decided by a coin toss.


Sanders' camp has not conceded defeat, considering it a tie, and his campaign manager told CNN he hoped to see a detailed breakdown of results in what is a famously complex caucusing process.

"We're not contesting the election," Jeff Weaver told CNN. However, he said, "we would love to see some tally sheets."

"There's new technology and room for human error."

Sanders himself was claiming a victory of another sort.

"We started our campaign 40, 50 points behind," he told CNN. "I am proud of bringing a whole lot of young people into the political process that would revitalize American democracy."

The upbeat tone was in stark contrast with Trump, who struggled to mask his disappointment in the immediate aftermath in Iowa. 

The 69-year-old showman said he was "honored" to finish second after being given no chance to win Iowa at the outset -- before he began dominating the air waves, thanks partly to a series of controversial remarks on Muslims and immigration.

But a second hiccup -- if his poll lead in New Hampshire fails to translate into votes -- could spell political disaster for the man who built his personal brand on the concept of winning, and has always said being second was tantamount to being nowhere.