Property billionaire Donald Trump has announced he will run for the White House in the 2016 election.
Mr Trump, a Republican, has never run for the party's nomination before, but has often talked about it.
"I am officially running for president of the United States and we are going to make our country great again," he told supporters at New York's Trump Towers on Fifth Avenue.
He said his fortune would allow him to be an effective president.
"Our country is in serious trouble. We don't have victories anymore," he said.
"When was the last time anyone saw us beating, let's say, China in a trade deal?
"They kill us. I beat China all the time."
Mr Trump expressed support for gun rights and said he would protect US government programmes like Medicare, Medicaid and Social Security.
And he said he would "immediately terminate" President Barack Obama's executive order on immigration, which would save undocumented migrants from deportation.
"Sadly, the American Dream is dead", Mr Trump said.
"If I get elected president I will bring it back bigger and better and strong than ever before. We will make America great again."
He becomes the 12th Republican to declare, with Wisconsin Governor Scott Walker and Florida's former governor Jeb Bush among the early frontrunners.
On the Democratic side, Hillary Clinton is the clear frontrunner.
The declared US presidential candidates
- Hillary Clinton, former First Lady and Secretary of State
- Martin O'Malley, former governor of Maryland and mayor of Baltimore
- Bernie Sanders, independent senator from Vermont, caucuses with the Democrats
- Lincoln Chafee, former senator and governor of Rhode Island
- Jeb Bush, former Florida Governor
- property mogul Donald Trump
- Ted Cruz, Texas senator and conservative firebrand
- Rick Santorum, Christian conservative from Pennsylvania
- Marco Rubio, Florida senator since 2011
- George Pataki, former three-term governor of New York
- Ben Carson, author and neurosurgeon
- Carly Fiorina, former boss of Hewlett Packard
- Mike Huckabee, former governor of Arkansas
- Rand Paul, libertarian conservative Kentucky senator
- Lindsey Graham, South Carolina senator since 2003
- Rick Perry, former Texas governor