Donald Trump has vowed to make America great again but his campaign has also been dominated by controversial remarks on immigration - such as deporting all Muslims and closing off the border with Mexico. He's one of the world's richest men, fond of telling crowds he's the ultimate dealmaker. And according to one poll, voters think he's the better bet for handling the economy than Democratic rival Hillary Clinton. But critics say his economic policies aren't credible.
"Ladies and gentlemen, I am officially running for president of the United States and we are going to make our country great again," Trump said.
Donald Trump has upended American politics... a billionaire property mogul and the richest candidate ever to run for President.
His outsider appeal and blunt catchphrases helped him demolish Republican rivals "Our leaders are stupid.. stupid.. stupid... They're stupid."
And he says his deal making prowess qualifies him for running the economy.
"We lose on everything, so we're going to negotiate and re-negotiate trade deals, military deals, many other deals that's going to get the cost down for running our country very significantly," he said.
In his manifesto and interviews, Trump also pledges to challenge China which he blames for threatening American jobs. He'd cut taxes and also abandon free trade deals - again to protect US jobs from competition. He also says he will wipe out America's entire debt -- 19 trillion dollars even suggesting he could renegotiate or refinance U.S. obligations.
But countries a fraction of the size of the U.S. that have tried to renegotiate debts have caused financial pandemonium -- Greece and Argentina, for example.
Analysts say it's just not credible for the world's biggest economy to try this.
"He has talked about defaulting. Now that was such a terrible thing to say that he backed away but he backed away by in effect jumping from the frying pan into the fire. He said: 'Maybe we will just inflate our way it', which of course doesn't exactly send a signal of confidence to financial markets," said Dan Mitchell, senior fellow/Cato Institute.
Even so, Trump's populist instincts - protecting coal miners, for example - have helped him court some trade union rank-and-file who might otherwise opt for Democrats.
But most union leaders do not support Trump.
"Although he has been consistent in what he has said, he has also been consistent in saying he wants to build a wall across the Mexican border. He wants to deport Muslims from this country. It's inconsistent with what real American policy is," said Paul Shearon from international federation of professional and technical engineers.
And yet those divisive positions are part of what's propelling Trump to the Republican nomination - while keeping one eye on what made him an American icon.