Donald Trump and Bernie Sanders resoundingly won Tuesday's presidential primaries in New Hampshire, riding a wave of anti-establishment anger in the second key test of the long, unpredictable race for the White House.
The runaway victory by Sanders, a self-described democratic socialist advocating nothing less than "political revolution," spelled a deflating if expected defeat for Hillary Clinton, who put a brave face on the loss and admitted she had some work to do as the campaign moves south.
On the Republican side, Trump's visceral assault on American politics galvanised voters who brought him his debut victory in the fledgling race, keeping him in pole position despite his second-place showing in last week's Iowa caucuses.
Ohio Governor John Kasich's uplifting and positive message of renewal catapulted him into second place, a potentially critical result for him as the Republican Party works out which mainstream candidate could successfully challenge the billionaire tycoon.
Disappointment befell Senator Marco Rubio, who hoped to match or better his third-place Iowa finish but stumbled to fifth in the Granite State, after he took a drubbing in Saturday's debate, where he robotically repeated his talking points.
Trump did what he had to do: secure a solid win after his embarrassing showing in Iowa called into question his showmanship strategy and his brand as a winner.
With 90 per cent of precincts reporting, Trump swept 35 percent of the vote to Kasich's 16 percent, with Iowa winner Ted Cruz at 12 per cent, narrowly ahead of former Florida governor Jeb Bush and Rubio.
Sanders, a US senator from Vermont who essentially treats neighbouring New Hampshire as his home turf, crushed Clinton by 60 per cent to 38 per cent, with 90 per cent of precincts reporting.
Officials predicted record voter turnout.
Sanders addressed a raucous crowd of supporters at his victory party in Concord, saying his primary win signalled voters no longer wanted business as usual in US political life.
"What the people here have said is that given the enormous crises facing our country, it is just too late for the same old, same old establishment politics and establishment economics. The people want real change," he said.
"Together, we have sent the message that will echo from Wall Street to Washington, from Maine to California."
Over at Trump headquarters, the crowd chanted "U-S-A! U-S-A!"
"We are going now to South Carolina. We're going to win in South Carolina," Trump declared, looking down the campaign trail to the next stop.
His win reinforced his position as the man to beat on the Republican side.
"He seems to be speaking for the silent majority," said auto mechanic Chris Skora after voting for the real estate magnate.
"A lot of us feel that way and it seems like in this day and age we can't say these things with the PC police all around."
CAMPAIGN 'NOT DEAD'
Exit polls showed Sanders winning every demographic group — a stunning result for an independent lawmaker and a potential warning sign for Clinton as she turns the campaign toward the next states that vote, Nevada and then South Carolina for the Democrats.
"I know I have some work to do, particularly with young people," Clinton conceded, as she recognised the American electorate's fury with establishment politics.
"People have every right to be angry," she said. "But they're also hungry, they're hungry for solutions."
Once every four years, the nation's eyes focus on New Hampshire, the small northeastern state home to just 1.3 million people that holds the first state primaries after the Iowa caucuses kick off the US presidential nomination process.
New Hampshire could help whittle down a crowded Republican field, with those fairing poorly likely to see their campaign funding dry up as the race turns to multiple states where deep pockets are crucial.
Bush found himself fighting for his political life, but awkwardly insisted to supporters that "this campaign is not dead," and that he would roll on to South Carolina.
New Jersey Governor Chris Christie, for whom a strong New Hampshire showing was critical, signalled the end of the line might be near after he finished sixth.
He said he was returning home to "take a deep breath" before making a decision about his political future.
For the past 60 years or so, most of the candidates who ended up taking the White House won their party's primary in New Hampshire.
But tellingly, the last three presidents — Barack Obama, George W. Bush and Bill Clinton — were all elected despite losing in New Hampshire.
Sanders and Trump led in polls in the run-up to the vote but everything had still been to play for in the state due to the high number of registered independents, who can choose to vote in either party, and the famous last-minute nature of voters here.
Exit polls conducted by CNN showed that nearly half of Republican voters did not make their final decision about whom to support until the last few days.
Trump has energised broad swaths of blue-collar Americans, angry about economic difficulties and frustrated at what they see as their country losing its global stature.
But the race could be upended yet again if former New York mayor Michael Bloomberg were to launch an independent bid. He told the Financial Times he was "looking at all options."