DES MOINES: Ted Cruz felled long-time Republican frontrunner Donald Trump and Democrat Hillary Clinton was battled into a virtual tie with rival Bernie Sanders on Monday, as Iowans held the inaugural vote of the 2016 White House race.

Republicans in the rural midwestern state backed the ultraconservative Cruz for their party's nomination, leaving a humbled Trump in second place just ahead of Senator Marco Rubio, according to nearly complete results given by the party.

Iowans flocked to churches, gymnasiums and libraries to be the first voices officially heard in the boisterous months-long nominating process that leads to Election Day on November 8.

“To God be the glory!” exclaimed Cruz, claiming victory with 27.7 per cent of the vote and staking his claim to be the new standard bearer of the right.

“Tonight is a victory for courageous conservatives across Iowa and all across this great nation,” he said, clearly pleased that his heavy investment in campaigning in the deeply conservative state had paid off.

For Trump, a modest vote tally — just above 24 per cent — raised deep questions about whether showmanship can take him all the way to 1600 Pennsylvania Avenue.

The real estate mogul who has centered his campaign around being a “winner “tried to brush off the steep loss, saying he had been given no chance to win Iowa at the outset.

“I was told by everybody, 'Do not go to Iowa. You couldn't finish in the top ten',” he told supporters. “I said 'I have to do it'. “Rubio, whose star has risen in recent weeks, tried to capitalize on a strong showing and his status as the top mainstream Republican. He earned more than 23 per cent, according to the nearly complete party results.

“Tonight here in Iowa, the people of this great state sent a very clear message,” he said, training his fire on Democrats. “Tonight we have taken the first step but an important step towards winning this election. “-

Trash the establishment

Iowa Democrats also showed their doubt in their party frontrunner, with Clinton in a dead heat with Sanders, who has railed against Wall Street and money in politics.

With more than 95 per cent of precincts reported, Clinton was on 49.9 per cent and Sanders 49.6 per cent. “What Iowa has begun tonight is a political revolution,” said Sanders, a Vermont senator, as he focused on building a movement around campaign finance reform and a more equitable society.

“So you guys ready for a radical idea? Well, so is America,” Sanders said to cheers. “We are going to create an economy that works for working families not just the billionaire class.“

Clinton had been looking to lay to rest the demons of 2008, when she lost in Iowa to now-President Barack Obama, and pursue her quest for history by dealing a solid blow to her upstart challenger.

But she now faces another tough battle in Sanders' backyard, New Hampshire.

The former first lady signaled that would be a bruising battle.

“It is rare that we have the opportunity we do now, to have a real contest of ideas -- to really think hard about what the Democratic Party stands for and what we want the future of our country to look like,” she said.

Get out the vote

Experts had predicted that high turnout would benefit political outsiders, who have dominated the 2016 race so far. And so it proved.

“This is very chaotic but I'm happy that so many people showed up,” said Aaron Menick, a 21-year-old at a Democratic caucus at Drake University.

Activists in one Des Moines precinct reported turnout was three times higher than expected.

Armies of campaign volunteers have fanned out through the state in recent days, knocking on doors or manning phone banks to get out the vote, while candidates dominated the air waves with talk show appearances and a relentless barrage of campaign ads.

For many long-shot candidates, Iowa has spelled the end of the road.

Republican Mick Huckabee announced he was dropping out of the race, and sources close to Democrat Martin O'Malley said he would follow suit.

Even as votes came in, fourth place Ben Carson was forced to deny reports he was dropping out of the race. “Contrary to false media reports, Dr. Ben Carson is not suspending his presidential campaign, which is stronger than ever,” said campaign spokesman Larry Ross.