Watch: Why is JD Vance going after Abdul El-Sayed?

Vice-president JD Vance and Michigan Democratic senate candidate Abdul El-Sayed are in the midst of a war of words that is turning increasingly more personal.

At an event to support Republican candidate Mike Rogers, Vance warned El-Sayed to "keep my wife's name the hell out of your mouth", after the candidate appeared to suggest that Vance's late grandfather would not accept Second Lady Usha Vance, who is Hindu.

Why is Vance going after El-Sayed? The BBC's White House reporter Bernd Debusmann explains.