US President Donald Trump said on Friday he will formally announce his re-election bid at June rally in Florida.

The announcement rally is largely a formality as the president has already stated he will seek re-election and his election campaign is already in swing.

In a tweet Trump said the announcement will take place alongside his wife, first lady Melania Trump, Vice President Mike Pence, and second lady Karen Pence on June 18 in Orlando, Florida.

Unlike in the 2016 presidential election, when Trump came into a crowded field of Republican candidates as an outsider, he now has the full backing of the Republican establishment.

The Democrats have a crowded field over 20 candidates vying for their party's nomination.