Anthony Alfieri, a professor at University of Miami School of Law in Coral Gables, Florida, told Newsweek that, no matter what the defense lawyers throw at Cohen, it won't overcome what has already been established by other witnesses and through banking and other documents.

Donald Trump's former lawyer Michael Cohen testified at the former U.S. president's criminal trial this week, asserting he had Trump's "signoff" to buy a porn star's silence and undergoing a cross-examination by Trump's lawyers.

Donald Trump's former fixer Michael Cohen faced aggressive questioning on Tuesday from the Republican presidential candidate's defense lawyers, who sought to undermine Cohen's testimony that Trump was intricately involved in a scheme to buy a porn star's silence.

Important details of the June and September events still need to be worked out after both sides come to quick agreement to debate.

Joe Biden has proposed two televised US presidential election debates, which rival Donald Trump quickly accepted. The first is proposed for 27 June and the second would be in September. The pair traded barbs on social media, with Mr Trump stating: "Just tell me when. Let's get ready to rumble!!!"