Charismatic Berlin mayor Klaus Wowereit, whose reputation has taken a beating in recent years by delays and cost overruns in the construction of the German capital's new international airport, says he will step down by the end of the year.

Wowereit told reporters Tuesday he would resign Dec. 11 after more than 13 years in office.

Berlin's first openly gay mayor, Wowereit helped turn the city into a top tourist destination. He coined its famous "Poor, but sexy" slogan, which helped attract hip youngsters from around the globe to the city's famous nightlife and highlighted Berlin's low living costs.

Wowereit, who still had two more years in office, says continued speculation over his future amid his plummeting popularity had made it difficult to govern.