The opposition's candidate for Istanbul mayor has launched his campaign for the June 23 re-run elections, promising to win again after Turkey's electoral board ruled the initial vote invalid.

Ekrem Imamoglu from the secular Republican People's Party is accusing President Recep Tayyip Erdogan's Justice and Development Party of cheating and of not accepting the result of the March 31 vote in the city of 15 million people.

He claimed Wednesday that the ruling party, which has governed Istanbul for years, worked to enrich itself.

Imamoglu supporters and party officials cheered their candidate who is running under the campaign slogan "everything will be very beautiful."

Erdogan's party pushed to void the March 31 results in Istanbul by claiming irregularities.