Former US Vice President Joe Biden has made reference to his Irish roots while on the campaign trail.

Speaking following a rally in South Carolina last night, Mr Biden told the Financial Times: "There's only one real Irishman running for president and it's me."

Joe Biden traces his Irish ancestry to counties Louth and Mayo.

Other Democratic candidates have Irish heritage including Beto O'Rourke, John Delaney and Tim Ryan.

Joe Biden's remark sparked criticism on social media from supporters of Beto O'Rourke.

His full name is Robert Francis O'Rourke.

Beto is a Hispanic nickname that he has had since he was a child.

During last year's Texas senate race, Donald Trump Junior accused Beto of being an "Irish guy pretending to be Hispanic."

At the time, he was asked by RTÉ News if his Irish heritage was important to him.

"The fact that I'm a Texan and an American is what is important to me but I will say that this country, five or so generations ago, accepted our family, the O'Rourkes," he said.