'A lying, dog-faced pony soldier': just what was Joe Biden talking about?

It was all going so badly for Joe Biden. And then it got worse.

Related: Sanders and Buttigieg campaigns request partial recanvass of Iowa caucuses – live

Concerns for the former vice-president’s 2020 bid were mounting after he was caught on camera calling a woman a “lying, dog-faced pony soldier” at a campaign stop in New Hampshire on Sunday.

When Madison Moore, a 21-year-old economics student, asked Biden whether voters could remain confident in his campaign after his poor performance in the Iowa caucuses, Biden asked her if she had ever attended a caucus. When Moore said yes, Biden responded: “No you haven’t! You’re a lying, dog-faced pony soldier.”

There didn’t seem to be any hard feelings – footage showed the audience laughing at Biden’s quip, and even Moore seems to be having a little giggle.

But his remark has still left people wondering what on earth Biden was referencing.

It’s not even the first time Biden has used the phrase. At a 2018 campaign event, talking about the Republican senator Kevin Cramer of North Dakota, Biden said: “As my brother, who loves to use lines from movies, from John Wayne movies … there’s a line in a movie where an Indian chief turns to John Wayne and says: ‘This is a lying, dog-faced pony soldier.’”

Biden’s spokespeople said the line comes from a John Wayne film – but it’s not clear it does. There is a 1952 western called Pony Soldier, but it does not star John Wayne, and no one is called a “lying, dog-faced pony soldier” in it, according to Slate. There is, reportedly, a line in the film in which a chief says: “The pony soldier speaks with a tongue of the snake that rattles.” Swings and roundabouts; dogs and rattlesnakes, I suppose.

For those worried about what the misattributed quote might do to Biden’s support, fear not. A recent video of Biden’s supporters chanting his name to the tune of Everybody by Backstreet Boys proves love is not only blind, but also deaf – they probably haven’t even noticed.