Obama tells "whining" Trump to drop rigged election accusations

US president Barack Obama has once again criticised the Republican candidate to succeed him, as he told Donald Trump to "stop whining" after the nominee claimed that the election will be fixed against him.

In a news conference at the White House on Tuesday, Obama questioned the leadership of the New York billionaire, saying that he should be concentrated on winning votes rather than contesting the result of the yet-to-happen election.

"I'd advise Mr Trump to stop whining and try to make his case to get votes," Obama said.

He added that the claims don't "show the kind of leadership and toughness that you want out of a president, if you start whining before the game's even over."

Trump has suggested that there has been collusion between his opponent Hillary Clinton and many mainstream media outlets in order to deny him a fair chance in the election.

"If whenever things are going badly for you and you lose you start blaming somebody else, then you don't have what it takes to be in this job," Obama added.

Trump and Clinton will face off for the last time in the third and final televised debate on Wednesday evening in Las Vegas, ahead of the election on November 8.