Democratic presidential candidate former Vice President Joe Biden speaks at a town hall event in Des Moines, Iowa, on Sunday. Democratic candidates raced across Iowa on Sunday in a last-minute flurry of rallies and hand-shakes ahead of the state's nominating vote that marks the official start of the US presidential election season. Iowa has traditionally served as a vital launching point - or burial ground - for presidential hopefuls. Photo: AFP

 

Former US vice president Joe Biden drew criticism on Sunday after he called a woman a "lying dog-faced pony soldier" at a campaign event in New Hampshire.

In an exchange widely shared on social media, 21-year-old Georgia college student Madison Moore asked the presidential hopeful to explain his poor performance in the Iowa caucus in the previous week.

"It's a good question," replied Biden, whose status as national frontrunner for the Democratic nomination was shaken by a damaging fourth-place showing in Iowa's caucuses.

"Have you ever been to a caucus?" he asked the Mercer University student, who nodded. "No, you haven't," Biden said. "You're a lying, dog-faced pony soldier."

Biden's campaign press secretary Remi Yamamoto tweeted the comment was a joke. "It's from a John Wayne movie and he's made it plenty of times before."

But the remark still drew criticism online, with many Twitter users saying the remark was not funny.

"If he can't handle a simple question from one of his own supporters, how can Joe Biden possibly take on Donald Trump one on one for six months?" tweeted Donald Trump Jr, the US president's son.

Moore told The Washington Post it was "totally irrelevant whether I've been to a caucus or not."

"Joe Biden has been performing incredibly poorly in this race. His inability to answer a simple question from a nobody college student like me only exacerbates that reality," she said.