Trump dealt blow by Cruz in Iowa vote. Democratic race against Bernie Sanders too close to call but Republican Ted Cruz humbles Donald Trump in first contest of US presidential campaign
Texas Senator Ted Cruz has won the Iowa Republican caucuses, the first vote to choose US presidential candidates.
"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 frontrunner Donald Trump, and Marco Rubio.
Votes in the Democratic race are still being counted, with Hillary Clinton's camp saying they have narrowly won.
Live updates: Iowa votes
The aim of the primary and caucus races in the coming months is to determine which candidates will stand for the two main parties in the November presidential election.
Iowa caucus results
Republican vote, 99% reported:
Ted Cruz: 28%, eight delegates
Donald Trump: 24%, seven delegates
Marco Rubio: 23%, seven delegates
Ben Carson: 9%, three delegates
Rand Paul, Jeb Bush: one delegate each. Chris Christie, Carly Fiorina, Jim Gilmore, Mike Huckabee, John Kasich and Rick Santorum: no delegates
Democratic vote, 99% reported:
Hillary Clinton: 50%, 22 delegates
Bernie Sanders 50%, 21 delegates
Martin O'Malley, 1%, no delegates