Republican presidential nominee Donald Trump has dug even deeper in his efforts to cast doubt on the legitimacy of the US 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 November 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. Early voting and voting by mail have begun in many states.
In another tweet later on Sunday, Trump blamed "animals representing Hillary Clinton" and Democrats in North Carolina for an overnight attack on a local Republican Party headquarters in that state.
Local authorities said the building in Hillsborough, North Carolina, had been struck through a front window with flammable material and an adjacent building wall was spray-painted with a swastika and the words "Nazi Republicans leave town or else."
"Animals representing Hillary Clinton and Dems in North Carolina just firebombed our office in Orange County because we are winning," Trump tweeted.
Clinton denounced the attack as "horrific and unacceptable" in her own tweet, adding: "Very grateful that everyone is safe.
Trump, a New York businessman, who has never held elective office, has often said the electoral process is skewed against him, including during the Republican nominating contests, when he disputed the method for winning delegates to the Republican National Convention.
His latest complaint of media bias stems from allegations by women that he groped them or made other unwanted sexual advances, after a 2005 video became public in which Trump was recorded bragging about such behaviour.
He apologised for the video but has denied each of the accusations.
