'I will work hard and never let you down! AMERICA FIRST,' Trump tweeted after being formally nominated
The Republican Party formally nominated Donald Trump for president of the United States Tuesday, capping a roller-coaster campaign that saw the billionaire tycoon defeat 16 White House rivals.
"It's my honour to be able to throw Donald Trump over the top in the delegation count tonight," the candidate's son Donald Trump Jr told delegates at the Republican National Convention which erupted in cheers and applause.
Trump - who was expected to address the gathering in Cleveland by video link later on Tuesday evening - welcomed the party's nomination as an "honor".
"Such a great honor to be the Republican Nominee for President of the United States. I will work hard and never let you down! AMERICA FIRST!" he tweeted.
The real estate mogul is expected to formally accept the nomination in a speech to the convention on Thursday, before facing off against Democrat Hillary Clinton in the November election.
The delegation of Trump's home state of New York cast the deciding votes that put him over the threshold of 1,237, the majority-plus-one of delegates to the convention in Cleveland, Ohio.
"It's unbelievable. It's surreal. I'm so proud of my father," Trump's eldest daughter and businesswoman Ivanka Trump, told CNN on the convention floor.
"He's the ultimate outsider and he did it. We are so proud of him."
Trump clinched the nomination nearly two months ago. But relentless controversy over his campaign rhetoric and a simmering movement by anti-Trump delegates to deny him the nomination made it less than a foregone conclusion.
It was not the smoothest of votes, with two Colorado delegates abstaining and the delegation of the capital Washington declaring their votes for Senator Marco Rubio and Ohio Governor John Kasich, only to have them flipped to Trump by the convention chair in order to follow party rules for the district.
But for the most part the state delegations closed ranks behind the nominee, after a fractious opening day, when chaos broke out on the floor as anti-Trump delegates launched a short-lived revolt.
The candidate's wife Melania Trump brought some pizzazz to the proceedings on the opening night as the Trump team sought to get the event back on track.
But an embarrassing plagiarism scandal tarnished her prime-time speech - and brought her husband's presidential campaign under withering scrutiny.
With millions watching on television, the Slovenia-born former model delivered a seemingly heartfelt defence of her husband.
"Donald is, and always has been, an amazing leader," said the 46-year-old. "Now, he will go to work for you."
But there were unmistakable similarities between her remarks and a speech given by Michelle Obama at the 2008 Democratic convention.
While the controversy burned and social media erupted with mocking commentary, the Trump team appeared in chaos - with denials of wrongdoing, followed by tacit admissions, followed by attempts to insulate Melania.
Campaign chair Paul Manafort dismissed the whole kerfuffle as "absurd". Trump's supporters seemed equally unperturbed.
"There's just a passion for Donald, and his wife knocked it out of the park," said Robert Antonacci of the New York delegation.
"Who cares? It was her speech. I don't believe for a minute that Melania and Donald were sitting around going, 'Hey, let's plagiarise Michelle Obama's speech.'"
Some Republican establishment figures - whose party was once respected for its discipline and public unity - suggested Melania's speechwriter be fired and defended Trump as a candidate.
"The distraction gets you off message a little," said Republican Party boss Reince Priebus, though he added that he expected the flap to fade quickly.
Clinton wasted no time seeking to capitalise on Trump's party victory.
"Donald Trump just became the Republican nominee. Chip in now to make sure he never steps foot in the Oval Office," she said in a fundraising tweet.
Trump won a thumping victory in a series of statewide party elections in 2016, garnering more than 13 million votes - the most of any Republican nominee ever.