Donald Trump said Vice President Mike Pence and his wife Karen will also be part of the event (File)

US President Donald Trump said Friday that he would formally announce his bid for re-election in 2020 on June 18 at a rally in Florida -- a state that was key to his victory in 2016.

Trump's wife Melania, Vice President Mike Pence and his wife Karen will also be part of the event in Orlando at the Amway Center arena, Trump said on Twitter.

"I will be announcing my Second Term Presidential Run... on June 18th in Orlando," he said. "Join us for this Historic Rally!"

Trump will launch his campaign against the backdrop of mounting Democratic calls for his impeachment, including by several of the nearly two dozen members of the opposition party seeking to unseat him.

I will be announcing my Second Term Presidential Run with First Lady Melania, Vice President Mike Pence, and Second Lady Karen Pence on June 18th in Orlando, Florida, at the 20,000 seat Amway Center. Join us for this Historic Rally! Tickets: https://t.co/1krDP2oQvG - Donald J. Trump (@realDonaldTrump) May 31, 2019

For now, the Republican president has focused his energy -- and fiery criticism -- on Democratic frontrunner Joe Biden, the former vice president.

Biden, a six-term senator before serving as No. 2 to president Barack Obama, has taken a substantial lead in early polling. Trump has referred to him as "Sleepy Joe" -- and even "SleepyCreepy Joe."

In November 2016, Trump defeated Democrat Hillary Clinton to win the White House.

Biden styles himself, like Trump, as an ardent defender of working class Americans, someone who can win back the Midwestern, white, male blue-collar voters who went for the Republican in 2016.