President Donald Trump has declared that any vote that came in after election day will not be counted.
Trump, who is at the verge of losing the US presidency to Democratic challenger Joe Biden, made the declaration on Thursday.
It is not yet clear how Trump, who has no power to declare any vote invalid, intends to void post-election day ballots. But US law does say votes cannot be cast after election day.
Trump could, therefore, head to court to challenge the polls. The president has seen his lead in battleground states eroded as millions of mail-in ballots, most of them for Biden, arrive after voting were closed.
Biden, who is already preparing a transition team, had said all votes must be counted. But the Trump campaign insists that only valid ballots matter.