Republican vice presidential hopeful Carly Fiorina stunned audiences as she was announced as Ted Cruzs running mate, by singing a song about the candidates family.

As Senator Cruz, who is currently polling second behind Donald Trump in the GOP race, announced his former rival Fiorina as his running mate, she broke into song, praising his wife and daughters.

Fiorina said: We have been travelling around the country and I have come to know Ted and Heidi and Caroline and Catherine, adding in song: I know two girls that I just adore, Im so happy I can see them more. Cos we travel on the bus all day, we get to play, we get to play.

She told the audience at a rally in Indianapolis, Indiana: I wont bore you with any more of the song but they have four verses, Caroline and Catherine, love you girls.

Following her outburst of song, users on social media widely shared footage of her ditty, mocking the singing, with several Twitter users suggesting it was the stuff of nightmares.

Fiorina, a former CEO of Hewlett Packard, dropped out of the GOP race in February after placing poorly in the New Hampshire Primary, and threw her support behind Cruz a month later.

As Cruz announced Fiorina as his running mate, he said: Carly is brilliant and capable, and yet she experienced the hardscrabble world of being a female professional, Reuters reported.

Over and over again, Carly has shattered glass ceilings. But in addition to being a woman of extraordinary experience, shes also a woman of deep principle.

He added: Carly is a vice presidential nominee who I think is superbly skilled, superbly gifted at helping unite this party.