US President Joe Biden has warned any candidates who refuses to accept defeat in next week’s midterm elections could set the nation on “the path to chaos”.
He also urged Americans to unite in opposition to “political violence” in the vote on the 8 November.
Mr Biden, a Democrat, said former President Donald Trump and his supporters were peddling “lies of conspiracy and malice”.
Republicans hit back that Mr Biden was seeking to “divide and deflect”.
Control of both chambers of Congress and key state governorships are hanging in the balance in next week’s elections.
Most forecasts suggest Republicans will win control of the House of Representatives, while the Senate could go either way.