US President Donald Trump says he will declare himself the winner of the election "only when there's victory".
There has been concern that Mr Trump will declare victory early, before vote counts are definitive, but the Republican president told Fox News there was no reason to "play games".
He told the Fox & Friends program he thought he had a "very solid chance at winning".
Mr Trump said he believed his large rally crowds during the campaign were the "ultimate poll" and translated into a lot of votes.
A digital US flag on the One World Trade Centre building on Election Day. Source: Maria Khrenova/TASS/Sipa USA
The president later predicted victory but admitted he could lose while visiting his campaign headquarters just outside Washington, DC.
"I think we're going to have a great night but it's politics and it's elections and you never know," Mr Trump said during his visit to thank staffers who worked to get him re-elected.
He said his campaign was doing well in states such as Florida, Arizona and Texas, and noted the importance of winning Pennsylvania.
"Winning is easy. Losing is never easy," he said on Tuesday. "Not for me it's not."
Supporters cheered and applauded the president at the Republican National Committee's annex in Arlington, Virginia, after Mr Trump spent days of gruelling campaigning on the road.
"After doing that many rallies, the voice gets a little choppy," Mr Trump said with his now-gravely delivery.
Mr Trump said success would bring unity. He listed what he believed were his accomplishments with the coronavirus and the economy.
The president has invited hundreds of supporters to an election party at the White House on Tuesday night while he watches the results come in.
