1990-2005, Member of the Lower Saxony State Parliament. 1998-99 and 2003-05, Chairman, SPD Parliamentary Group. 1999-2003, Prime Minister of Lower Saxony. November 2005 - October 2009, Federal Minister for the Environment, Nature Conservation and Nuclear Safety. Since 2005, Member of Parliament. Since December 2013, Federal Minister of Economic Affairs and Energy. Member (for more than 35 years) and since November 2009, Chairman, Social Democratic Party of Germany (SPD).