US President Donald Trump has called for himself and his Democratic opponent Joe Biden to submit to a drug test before their first presidential debate.

Trump told the Washington Examiner that he had noticed a sudden improvement in Biden’s performance in the Democratic Party debates, suggesting he might be on drugs.

Mr Trump told the Washington Examiner that he thought Mr Biden was “incoherent” during debates with almost a dozen other Democratic candidates. But, suddenly, when the field was down to just himself and Mr Sanders, the president claims he saw a different former VP on the debate stage.

Notably, Mr Trump made similar remarks in the fall of 2016, positing that then-opponent Hillary Clinton had taken drugs.

It is to be noted here that Biden and Trump will have three debates before the election.