Texas Senator Ted Cruz has won the Iowa Republican caucuses, the first vote of the US 2016 presidential election.
“Tonight is a victory for courageous conservatives,” he declared, to great applause, as he railed against Washington, lobbyists and the media.
He took 28% of the Republican vote, beating his rival, the once frontrunner Donald Trump, and Marco Rubio.
Votes in the Democratic race are still being counted, and suggest a tight race between the two leading candidates.
With 85% of results in, frontrunner Hillary Clinton and self-proclaimed Democratic socialist Bernie Sanders are less than 1% apart.
Mr Trump congratulated the Texas senator and said he was “honoured” by the second-place finish.
At least two candidates are dropping out following the results.
Sources close to Democrat Martin O’Malley, former Maryland governor, have told the BBC that he will suspend his campaign – narrowing the field to two competitive candidates.
On the Republican side, Former Arkansas Governor Mike Huckabee tweeted that he too would suspend his campaign.
More on Senator Ted Cruz
What would a Cruz presidency be like? Imagining the first terms of Mr Cruz and other candidates
Three things Ted Cruz says: A 60-second summary of the Republican candidate’s stump speech
The Texan Tea Partier: Ted Cruz’s rapid, rocky ascension to presidential candidate
How does a US election work? If you want to be president, it helps to be governor, senator, or five-star military general – and have lots of patience
Special report: The BBC’s full coverage of the race to the White House
Iowa has an unusual election system called a caucus, which involves people gathering at private homes, schools and other public buildings across the state.
Democratic voters divide themselves into groups based on their preferred candidate, but the Republican caucus process is more like a traditional ballot.
Over the coming months, the other 49 states as well as US territories will vote for the party nominees.
Each states’ delegates will be tallied and a nominee will become apparent as the summer draws near.
In November, the US will pick who its next president will be. He or she will assume office in January 2017.