TOKYO — First, a rat gnawed through exposed wiring, setting off a scramble to end yet another blackout of vital cooling systems at the Fukushima Daiichi nuclear plant. Then, hastily built pits for a flood of contaminated water sprung leaks themselves. Now, a new rush of radioactive water has breached a barrier built to stop it, allowing heavily contaminated water to spill daily into the Pacific.

As the scope of the latest crisis became clearer Wednesday, Japan’s popular prime minister, Shinzo Abe, ordered his government to intervene in the cleanup of the plant — taking a more direct role than any government since the triple meltdowns in 2011 qualified Fukushima as the world’s second worst nuclear disaster.

Abe, a staunch defender of the country’s nuclear program, appears to have calculated that he needed to intervene to rebuild public trust and salvage a pillar of his economic revival plan: the restarting of Japan’s many idled nuclear plants. That trust has been eroded not only by the original catastrophe, but also by 2½ years of sometimes dangerous missteps by the plant’s operator, Tokyo Electric Power Co., or TEPCO, and what many Japanese see as the company’s continuing attempts to mislead the public and cover up deteriorating conditions at the plant.

“This is not an issue we can let TEPCO take complete responsibility of,” Abe told a group of Cabinet ministers as they gathered to discuss the water problem that has swiftly emerged as the biggest challenge at the plant. “We must deal with this at the national level.”

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Many analysts said Abe’s move was an admission that previous governments had erred by entrusting the 40-year, $11 billion cleanup to the same company that many blame for allowing the catastrophe to happen in the first place.

The groundwater problems at the plant started soon after the disaster, when TEPCO realized that tons of water flowing from the mountains and toward the sea were pouring into the contaminated reactor buildings, filling their basements with water that had to be pumped out. On Wednesday, government officials said they believed 300 tons, or 75,000 gallons, of the tainted water was entering the ocean daily.

It was also not entirely clear how intensively the government would actually get involved in the cleanup, or whether it will allow TEPCO to remain in charge. Abe did not give specifics beyond directing his ministers to help resolve the water problem.

On Wednesday, local news reports quoted unidentified officials in the Ministry of Economics, Trade and Industry as saying that Tokyo would likely help pay for a $400 million wall of ice that is being planned to surround the damaged reactor buildings.

The plan calls for freezing the soil around the reactor buildings to keep out groundwater before it can become contaminated. The wall would run nearly a mile in length and reach almost 100 feet into the ground. Officials said no wall of ice on such a scale has ever been attempted before.