Mike Moore has announced he is leaving his post as New Zealand ambassador to the United States.
The former Prime Minister suffered a stroke in April this year and a statement given to his staff today says next month will be his last in Washington.
After leaving politics, Mr Moore became director-general of the World Trade Organisation.
Trade was a focus during his time as ambassador too, as the Trans Pacific Partnership (TPP) was negotiated.
"I am now the longest serving continuous ambassador to the US. I didn't seek this job but felt I should do it because great issues were at stake. The time was ripe for it," Mr Moore said.
"On a security level things have moved up several notches. You are aware of the many exercises we do together and the important contribution we are making in the struggle against Isis.
"TPP was the second part of the job and we have worked to getting acceptance for this by Congress. I believe it will be forthcoming. It will be a question of time."
Mr Moore was Prime Minister of New Zealand for only two months in 1990, as the fourth Labour government imploded during its dying days.
His statement makes reference to this.
"In my political life I have always been in the wrong place at the wrong time but the mission I was given here was correct and the timing was right."
Mr Moore then addressed his staff.
"I want to thank you and your families for your commitment and to apologise for walking past you in the building full of ideas and full of hope.
"If I forgot to say hello or thank you that was my mistake.
"We will go home content that we did our best. Pity the old body gave up."
Mr Moore's last day in Washington will be December 16.
He said after losing a couple of weeks for tests and surgery, he won't be able to have a special farewell function. Instead, it will combine with the Christmas party there.
Mr Moore thanked foreign minister Murray McCully and the Ministry of Foreign Affairs and Trade for their kindness to him as his wife Yvonne.