Swiss Foreign Minister Didier Burkhalter sent his resignation to parliament in a surprise move today, saying he plans to leave government on October 31.
Burkhalter did not say what he plans to do once he steps down, telling journalists the realisation that it was time to go had suddenly hit him "like a wave" on Sunday.
In his letter to parliament, he said that "after 30 years of political engagement, including the last eight years in the national government, I naturally feel the need to soon write a new page in my life".
"I do not yet know which ink I will use, but I think I will use more colours that are more personal and less publicly visible," he wrote in his letter.
The 57-year-old member of the Liberal Party insisted to journalists that he felt "no bitterness. I just want to do something else".
He was first elected to government, or the Federal Council, in 2009, first as interior minister before taking the foreign affairs portfolio in January 2012.
In 2014 he held Switzerland's rotating one-year presidency, during which time he was hailed for his role heading the Organisation for Security and Cooperation in Europe just as the Ukraine conflict was escalating.
Burkhalter is a widely respected diplomat who saw his name mentioned as a possible candidate to take the helm of the United Nations when former chief Ban Ki-moon stepped down -- a position since filled by Portugal's former prime minister Antonio Guterres.
Today, he was asked if he might not fill the shoes of Norway's former prime minister Thorbjorn Jagland as head of the Council of Europe, but answered: "I have not asked myself that question".
"I still have four months left as minister," he added.