This year's US presidential election will likely be a rematch between President Joe Biden and former President Donald Trump, now that both men have clinched their respective party's nominations.

The Associated Press and other US media outlets say Biden earned the necessary number of delegates to become the Democratic Party's presumptive presidential nominee, after winning Tuesday's primaries in Georgia and other states.

Media reports say Trump also secured the required delegates to become the Republican Party's presumptive nominee.

Biden issued a statement saying he is honored that a broad coalition of voters has put their faith in him again to lead the party and the country, as "the threat Trump poses is greater than ever."

Trump said in a social media post that the Republican Party is united and strong, and running against "the Worst, Most Incompetent, Corrupt, and Destructive President in the History of the United States."

He urged voters to make America great again.

The political news website RealClearPolitics says polls suggest a close race in a possible Biden-Trump rematch.

Biden had an average support rate of 45.7 percent against Trump's 47.4 percent as of Tuesday.