Japanese opposition parties submitted a no-confidence motion against Prime Minister Naoto Kan, who refused to resign earlier Wednesday over his handling of the crisis caused by the March 11 earthquake and tsunami.
"What is most sought by the people is for us to work together to achieve reconstruction and resolve the nuclear crisis," Kan said during a heated parliamentary debate with opposition leaders. "I must respond to their needs and that is my responsibility."
He is most likely to survive the motion because his Democratic Party of Japan controls the powerful lower house of parliament. Dozens of lawmakers may support the motion to pressure Kan into resigning, a move that could split his party, but their participation would be still short of the majority.
A vote is expected Thursday.
A magnitude 9.0 quake and massive tsunami on March 11 damaged cooling systems at the Fukushima Dai-ichi nuclear plant, causing its three reactor cores to largely melt and spewing radiation into the air _ the worst nuclear crisis since Chernobyl in 1986.
More than 24,000 people are dead or missing due to the disasters in northeastern Japan, and 80,000 residents have been forced to evacuate towns contaminated by the radiation-leaking plant.
Kan, who became prime minister just a year ago, has been criticized for delays in construction of temporary housing for evacuees, lack of transparency about evacuation information, and a perceived lack of leadership.
"You should step down," said Sadakazu Tanigaki, head of the largest opposition group Liberal Democratic Party. "It's impossible to achieve disaster reconstruction under your leadership."
Tanigaki's party submitted the no-confidence motion along with two smaller opposition groups _ New Komeito and the Sun Rise Party. If it passes, Kan would have to order the resignation of his Cabinet or dissolve the 480-seat lower house for elections.
Local officials criticized national lawmakers for neglecting the disaster victims while indulging in their political game.
"We are going through a national crisis that must be tackled by nationwide effort. It's not time for political fighting," said Michio Furukawa, mayor of Kawamata, a town near the Fukushima nuclear plant.
In the 1990s, Kan was a crusading health minister who stood up to his own bureaucracy to lift the lid on a horrific AIDS scandal, but he was seen as an uninspiring prime minister even before the earthquake with a popularity rating below 20 percent.
He emerged as prime minister last June only after other leaders of his Democratic Party fell. He already is Japan's fifth leader in four years.