Election being rigged at many polling places - Trump

Republican presidential nominee Donald Trump dug deeper in his efforts to cast doubt on the legitimacy of the U.S. election, saying on Twitter on Sunday that he believed the results were being "rigged" at many polling places.

His tweet came hours after his vice presidential running mate, Mike Pence, said Republicans would accept the outcome of the Nov. 8 contest between Trump and his Democratic rival, Hillary Clinton.

"The election is absolutely being rigged by the dishonest and distorted media pushing Crooked Hillary - but also at many polling places - SAD," Trump wrote on Twitter, in the latest of a series of comments he has made over the past several days calling into question the fairness of the election.

Trump, who is trailing Clinton in opinion polls, did not provide any evidence to back his allegations of impropriety at the voting booth.