Donald Trump has officially kicked off his re-election campaign for 2020.
His new campaign slogan - "Keep America Great" - was greeted with boisterous cheers at the rally in Florida.
Mr Trump complained he had been "under assault from the very first day" of his presidency by a "fake news media" and "illegal witch hunt" that had tried to keep him and his supporters down.
He also painted a picture of what life would look like if he loses in 2020, telling the crowd that Democrats "want to destroy you and they want to destroy our country as we know it".
"A vote for any Democrat in 2020 is a vote for the rise of radical socialism and the destruction of the American dream," he said.
Crowds at Trump's rally in Orlando, Florida
Mr Trump spoke fondly of his 2016 campaign, calling it "a defining moment in American history".
And he said that, in the years since, he had fundamentally upended Washington, staring down "a corrupt and broken political establishment" and restoring a government "of, for and by the people".
Despite Tuesday night's launch, Mr Trump officially filed for re-election on January 20, 2017, the day of his inauguration, and held his first 2020 rally in February, 2017, in nearby Melbourne, Florida.
He has continued holding his signature "Make America Great Again" rallies in the months since.
Just before the rally began, Mr Trump tweeted that from next week, he "will begin the process of removing the millions of illegal aliens who have illicitly found their way into the United States".
Early Democratic front-runner Joe Biden said on Tuesday that Mr Trump's politics are "all about dividing us" in ways that are "dangerous - truly, truly dangerous".
Another leading Democratic contender, Bernie Sanders, said Mr Trump had delivered "an hour-and-a-half speech of lies, distortions and total, absolute nonsense".