Klaus Wowereit By Superbass (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Charismatic Berlin mayor Klaus Wowereit, whose reputation has taken a beating over struggles in the construction of the German capital's new international airport, said Tuesday he will step down by the end of the year.

Greg Kabel

Wowereit told reporters 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.

Wowereit 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. He said he was grateful to have been in charge as "Berlin became an international metropolis."

"It's good that the city has internationalized itself, but it's also as important that the city remains livable," the Social Democrat said.

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.

"The decision did not come easily," he said.

He said his "greatest defeat" was that the Willy Brandt airport planned for the capital has not yet opened.

It was first scheduled to be ready late 2011 but has been repeatedly delayed. Costs have more than doubled to some 5.4 billion euros ($7.1 billion) and it is still not clear when it will open.

Wowereit governed for a decade in a coalition with the formerly communist Left Party, but had to form a coalition with the state branch of Chancellor Angela Merkel's Christian Democrats after elections in 2011.

National Left Party leader Gregor Gysi said that while Wowereit leaves behind him the airport debacle and other issues, he should also be given credit for an "important chapter in the development of Berlin."

"He had a big role in ensuring that the German capital has become a metropolis. Especially culturally Berlin has significantly advanced," Gysi said in a statement.

"It was also to Klaus Wowereit's great credit that he was the first politician to openly declare his homosexuality, which clearly gave great support to the fight for equality by lesbians and gay men."