The popular 55-year-old mayor of Germany's second largest city, a state in its own right, is a state premier in all but title. He is the latest in a line of leading members of Chancellor Angela Merkel's Christian Democratic Party (CDU) to throw in the towel.

"There's a time for everything," von Beust told reporters in Hamburg on Sunday, listing the positions he has held in Hamburg. "This, naturally, applies to me as well." He said he had contacted Merkel to tell her of his resignation and that she had been "understanding."

"We've accomplished a lot for Hamburg - the global economic crisis has left Hamburg largely unscathed," von Beust said. "I'm sure the good work will continue even without me."

Leaving office alongside von Beust are Karin von Welck, Hamburg's senator for culture, and Volkmar Schoen of the senate chancellery. Many in the CDU expect current Christoph Ahlhaus, who is currently the interior senator and seen as considerably more conservative than von Beust, to take over as mayor at the end of August.

Von Beust has been suffering form fatigue in his mayoral duties and has lost his appetite for politics altogether, aides have told German media.

Cross-party appeal

Charismatic speaker, often touted as Merkel's potential understudy, von Beust helped the CDU reach new urban voter demographics that the traditionalist party had often ignored.

The openly gay, centrist conservative conquered the traditionally left-leaning port city of Hamburg for the Christian Democrats (CDU) in 2001, after the party had spent 44 years in opposition. He has retained the post ever since, and even ruled with an absolute majority - a rare occurrence under Germany's electoral system - between 2004 and 2008.

Von Beust had been governing Hamburg in coalition with the Green party - the highest-profile alliance in the history of two parties considered at opposing ends of the political spectrum - and the city has been running relatively smoothly despite the right-left divide.

Von Beust added that he did not have "the slightest doubt" that the CDU-Greens coalition would be able to continue its work without him.

As Hamburg law calls for all of the city's senators, who serve in positions similar to ministers in other German states, to be reconfirmed in office if the head of government steps down. It remains to be seen if the rest of Hamburg's government will remain in office or if early elections will be held.

One area of legislation where the parties have struggled is an adaptation to the city's schooling system. Also on Sunday, Hamburg's electorate is voting on a referendum over the proposal.

Thinning ranks

Merkel's popularity has sunk to its lowest level since she was elected chancellor in 2005, and an exodus of senior CDU politicians has hardly helped steady the ship as she walks the tightrope of trying to cement Germany's economic recovery while simultaneously cutting national public spending.

Von Beust is the sixth Christian Democrat state premier to leave his post in the last 10 months. Although Christian Wulff quit his job in Lower Saxony to be promoted to the role of German president, he was replacing perhaps the highest profile CDU-affiliated deserter of all, former President Horst Koehler.

The Welt am Sonntag newspaper said Sunday that the number of experienced leaders in Merkel's party was dwindling.

"It would not be entirely fair to give the chancellor all the blame for these departures, but at the same time she has to ask herself whether she has done enough for the top players on her team," it said. "The answer is no."

Finance Minister Wolfgang Schaeuble cast the changeover in the CDU in more positive light in an interview with the same paper.

"In other countries it's far more normal for political leaders to switch careers at some point," he said. "If there weren't any change, everyone would say: 'Oh, those are always the same people and there's no innovation.'"

The CDU remains the dominant party in German politics, despite its waning popularity. Of Germany's 16 states, 10 are ruled by premiers from the CDU or its Bavarian sister party the CSU. Only one of the 10, Peter Mueller of Saarland, has long experience at the helm of a regional government.

It seems only two CDU/CSU figures are to remain in government who are widely considered as potential chancellors, both of them hailing from Merkel's cabinet: Neither Germany's Minister of Labor and Social Affairs Ursula von der Leyen nor Defense Minister Karl Theodor zu Guttenberg have had executive experience at the local level running a German state or city-state.

Author: Mark Hallam, Catherine Bolsover (dpa, Reuters)
Editor: Sean Sinico