Just for Fun (1963)

With an election approaching, the two major political parties in England work desperately to capture the enthusiasm of teenagers, who have been granted the right to vote. When the prime minister cuts the quota of musical programs permitted on television, teenagers Mark and Cherry lead others youngsters in forming their own political party, which successfully utilizes popular recording artists in helping to win the election.

https://www.imdb.com/title/tt0057213/