TOKYO -- Prime Minister Naoto Kan defeated a no-confidence motion Thursday over his handling of Japan's triple disasters, but the victory may be short lived -- he said he is willing to resign once the country's recovery kicks in.

Buying himself some time and warding off a challenge that threatened to split his party and send Japan's government into a deeper morass, Kan won by a margin of 293-152 in the 480-seat lower house of parliament.

Kan, in office just one year, had been criticized for not responding swiftly enough to the crisis caused by the March 11 earthquake and massive tsunami that left more than 24,000 people dead or missing. The tsunami also crippled a nuclear power plant northeast of Tokyo, setting off radiation leaks and the evacuation of tens of thousands of people.

The disaster -- believed to be the costliest in history -- has been a huge drain on Japan's fragile economy. The head of the nuclear plant's operator already has resigned in disgrace, largely over criticism that the plant was not adequately prepared for such a large tsunami.

Before Thursday's parliamentary session, Kan urged lawmakers to let him stay on and push ahead with measures to bring the country through the crisis, but in a nod to his many critics, he acknowledged "shortcomings" and said he would consider stepping down after the recovery firms up.

"Once the post-quake reconstruction efforts are settled, I will pass on my responsibility to younger generations," he said. "The nuclear crisis is ongoing, and I will make my utmost efforts to end the crisis and move forward with post-quake reconstruction works."

Kan has been criticized for delays in the construction of temporary housing and a lack of transparency about evacuation information in the nuclear crisis. His government is also embroiled in a debate about compensation for victims.

Japan's government has said the cost of the earthquake and tsunami could reach $309 billion, with extensive damage to housing, roads, utilities and businesses. Japan's ballooning debt is already twice the size of the country's gross domestic product.

Kan did not specify a date or say how he would determine that the recovery was on track. Opponents immediately slammed that, saying Japan cannot afford to have a lame duck administration.

"If you are going to quit, quit now," senior opposition lawmaker Tadamori Oshima told Kan over a chorus of cheers and jeers in the parliament chamber. The main opposition group, the Liberal Democratic Party, introduced the no-confidence motion Wednesday along with two other opposition groups.

Japanese media reported Kan could stay on for a few months.

"I don't think it will be long," said Yukio Hatoyama, a ruling party member who preceded Kan as prime minister.

Hatoyama and dozens of other members of Kan's ruling Democratic Party of Japan have expressed concern with the prime minister's leadership, creating a deep rift. That has complicated Kan's efforts to unite the government behind his reconstruction plans, which involve a huge injection of funds and possibly tax increases.

Even Kan backers expressed concerns over his post-tsunami record.

"We admit Prime Minister Kan's crisis management was not perfect," said lawmaker Kazunori Yamanoi. "But passing a no-confidence motion and forcing him to step down and dissolve the parliament would only cause further delays in the reconstruction process."

March's magnitude 9.0 quake and the massive tsunami that followed damaged the Fukushima Dai-ichi nuclear plant, causing the worst nuclear crisis since Chernobyl in 1986. About 80,000 residents have been forced to evacuate towns contaminated by the radiation-leaking plant.

Kan's fortunes were sagging even before the crisis began, but have plummeted since.

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 resigned. He already is Japan's fifth leader in four years.