In 1972, Cass Elliot and John Denver appeared on Burt Sugarman's Midnight Special to perform Leaving in on a Jet Plane, but before they started the hit song, both Elliott and Denver told the audience to register to vote since it was an election year. Vietnam was still raging on at the time. "My issue is that it’s all very well to sit back and complain, but when it’s your country, you have a responsibility.