Former Prime Minister Tony Blair has paid tribute to David Miliband, following news of his resignation as an MP.
"I congratulate David on his appointment to a major international position. It shows the huge regard in which David is held worldwide. I'm sure he will do a great job. He is obviously a massive loss to UK politics.
"He was the head of my policy unit and then a truly distinguished Minister in the Government and remains one of the most capable progressive thinkers and leaders globally. I hope and believe this is time out not time over."
David Miliband was nearly Prime Minister, and nearly Labour party leader, but his brother's rise has led him to take a back seat.
David Miliband will resign as an MP to take up a job in America, a move which is set to be announced today.