Republicans formally chose Donald Trump as the party’s presidential nominee Tuesday, a landmark moment in American politics and a stunning victory for a man whose White House ambitions were once openly mocked.

Republicans formally chose Donald Trump as the party's presidential nominee Tuesday, a landmark moment in American politics and a stunning victory for a man whose White House ambitions were once openly mocked.

After a turbulent campaign that saw Trump defeat 16 rivals and steamroller stubborn party opposition, the tycoon said it was time to "go all the way" and beat Democrat Hillary Clinton in November.

"This is a movement," he told the delegates via video link.

On the convention floor, states from Alabama to West Virginia took it in turns to pledge their delegates.

It fell to Trump's home state of New York, represented by a coterie of the candidate's adult children, to hand him the majority-plus-one needed to clinch the nomination.

"It's my honor to be able to throw Donald Trump over the top in the delegation count tonight," Donald Trump Jr said to cheers and applause.

When the bombastic mogul came down the escalators of Trump Towers in New York 13 months ago to announce his candidacy, few experts gave him even the faintest chance.

His campaign has defied political norms -- embracing racially inflammatory policies, offending key voting blocks, eschewing big-spending advertising campaigns and relying on saturated media coverage above campaign structure.

"It's unbelievable. It's surreal. I'm so proud of my father," said Trump's eldest daughter and businesswoman Ivanka Trump, often described as his secret weapon.

"He's the ultimate outsider and he did it. We are so proud of him."