Washington, Nov 4 (IANS): As American voters all across the US cast their ballots to elect the country's new President, incumbent President Donald Trump acknowledged that it would be tough for him to face a potential defeat against his Democratic rival Joe Biden.

He made the remarks while visiting a re-election campaign office in Arlington, Virginia, on election day on Tuesday, The Hill news website reported.

"I'm not thinking about concession speech or acceptance speech yet. Hopefully, we'll be only doing one of those two.

"Winning is easy. Losing is never easy. Not for me it's not," he told reporters at the campaign office.

"Depending on the extent of victory," Trump also predicted that it could be clear which candidate has won the election by the end of Tuesday night.

"We should be entitled to know who won on November 3," he added, reviving his long-standing grievance about votes being counted beyond Election Day despite it being a standard practice.

Trump has repeatedly complained about Pennsylvania in particular, railing against a Supreme Court decision that allows the state to accept ballots received by November 6.

Without any proof, the President claimed on Monday that the ruling will "induce violence", and on Tuesday called it a "very dangerous decision", The Hill news website reported.

Trump has consistently trailed Biden in polling in the key swing states of Wisconsin, Michigan and Pennsylvania, and the two have been neck and neck in Arizona, Florida, Georgia and North Carolina.

Trump won all of those states four years ago.

During his visit to the office, Trump met dozens of staffers from the campaign and also the White House.

Most wore masks, other than a few of the President's closest advisers, including press secretary Kayleigh McEnany, senior adviser Jared Kushner and chief of staff Mark Meadows.

Trump will host a campaign party on Tuesday night, which will reportedly have hundreds in attendance.