Donald Trump is sporting a new baseball hat after his presidential win.

The red hat is familiar to many, but it now features the word "USA" instead of "Make America Great Again".

Perhaps in a dig to Green party candidate Jill Stein’s move towards a vote recount in three swing states, the new hat has the number 45 stitched to the side - referring to his soon-to-be position as 45th president of the US.

He was pictured in the new item of merchandise as he left his Florida Mar-a-Lago resort with his security entourage.

The hat is not yet available for sale, but his merchandise website does offer a Christmas ornament in the shape of a baseball hat. The president-elect also offered a 30 per cent discount on branded items through Black Friday and Cyber Monday.

Mr Trump was pictured in the new hat less than an hour after he sent a series of tweets about Ms Stein and her call for a vote audit.

"In addition to winning the Electoral College in a landslide, I won the popular vote if you deduct the millions of people who voted illegally," he claimed.

Ms Stein’s campaign to recount votes in Wisconsin, Pennsylvania and Michigan has raised more than $5 million in less than a week.

Hillary Clinton’s campaign said they would join her following a group of scientists and electoral lawyers claiming they found evidence that election results in the three states had been potentially hacked and manipulated.

"Because we had not uncovered any actionable evidence of hacking or outside attempts to alter the voting technology, we had not planned to exercise this option ourselves," Clinton campaign lawyer Marc Elias wrote in a post on Medium.

"But now that a recount has been initiated in Wisconsin, we intend to participate in order to ensure the process proceeds in a manner that is fair to all sides."