Japanese prime minister Naoto Kan has said he is resigning after almost 15 months in office.
Mr Kan's decision was widely expected amid sinking approval ratings and party infighting.
In June, he had promised to resign after politicians passed three key pieces of legislation. The final two bills cleared the parliament earlier.
The party will choose a new leader on Monday, who will almost certainly become Japan's next prime minister - the sixth since 2006.
Potential successors include former foreign minister Seiji Maehara, finance minister Yoshihiko Noda and trade minister Banri Kaieda.
Looking back on his year and three months in office, Mr Kan said he did all he could given difficulties he faced, including the disasters and a major election defeat in upper house elections last summer that left the parliament in gridlock.
"Under the severe circumstances, I feel I've done everything that I had to do," he said. "Now I would like to see you choose someone respectable as a new prime minister."
The 64-year-old Mr Kan has seen his approval ratings tumble amid a perceived lack of leadership after the March 11 earthquake and tsunami and subsequent nuclear crisis.
Survivors complain about slow recovery efforts, and radiation from the crippled Fukushima Dai-ichi plant has spread into the air, water and food supply.
Political infighting between the ruling and opposition parties also have discouraged the public. Recent polls show that his public support has fallen under 20%.