In sharp contrast to governments across the world that are moving to warn their citizens in Japan about radiation hazards and to reassess their own nuclear power programs, the Obama administration is pursuing a cautious course — standing firmly behind the U.S. nuclear industry.

As France and Germany advised their citizens to leave the Tokyo metropolitan area, the United States urged Americans to move beyond a 50-mile radius of the damaged Fukushima Daiichi plant. That’s farther than the 20-mile buffer imposed by the Japanese government, but short of an evacuation of the country.

And as governments from Berlin to Beijing this week were closing older nuclear plants for inspection or halting new permits, Obama administration officials reiterated support Wednesday for keeping nuclear power as a key part of U.S. policy and said there were no plans to shut down plants.

In recent days, White House officials have said that the U.S. program, with 104 plants, is safe and that the independent Nuclear Regulatory Commission monitors every facility.

Testifying on Capitol Hill, Energy Secretary Steven Chu told House members that the federal budget called for new nuclear plants. “That position hasn’t been changed,” he said.

The approach underscores the prominent role that nuclear power has played in President Obama’s broader energy agenda. He has called for investing in a range of energy sources — including wind, solar and nuclear power — in addition to oil to increase U.S. energy independence and reduce carbon emissions. As part of his 2012 budget request, Obama is seeking $36 billion in additional loan guarantees to help jump-start the costly process of building new nuclear plants.

But the administration’s stance also highlights the political challenges Obama confronts as he deals with energy policy. Republicans and many Democrats, eyeing rising gas prices, are pushing for more oil drilling in the Gulf of Mexico and elsewhere, in addition to a stepped-up commitment to nuclear energy. At the same time, in the wake of the gulf oil spill and as the Japan crisis unfolds, the White House faces pressure from many on the left to restrict drilling and rethink nuclear power.

Sen. Barbara Boxer (D-Calif.), questioning an NRC official in a Senate hearing, wondered about the response in the European Union, which has announced plans to test its plants for emergency preparedness.

“I would very much like to know why those respected allies of us have taken that action” while the United States has not, Boxer said.

Industry lobbyists said they were pleased with the administration’s reaction, suggesting that moving too quickly to halt building plans or interfere with plant operations would create more problems than it would solve.

NRC Chairman Gregory Jaczko said Monday that the agency “will always take whatever steps are necessary to ensure the safety and security of nuclear power plants in this country.” He said that “right now, we believe we have a very strong program in place.” Since then, some critics have tried to apply more pressure.

Rep. Edward J. Markey (D-Mass.) called for a moratorium on new construction in seismically active areas and for additional safety measures at existing plants. Another Democrat, Sen. Richard Blumenthal of Connecticut, sent a letter to the NRC asking whether the United States can learn lessons from the Japan disaster. Blumenthal wrote that the crisis has “raised concerns — expressed to me by Connecticut residents — about whether a similar problem could occur in the United States.”

The Union of Concerned Scientists plans to issue a report Thursday assessing 14 “near misses” last year at U.S. nuclear plants and is urging the Obama administration to reconsider its stance.

“To run around and basically say this can’t happen here and we need to move forward is not really the message I would be coming out with right now,” said Ellen Vancko, the union’s nuclear energy and climate change project manager.

Dave Hamilton, director of global warming and energy programs at the Sierra Club, said that the Obama administration appears trapped by its efforts to use nuclear power to attract Republican support for its energy policies.

“They’ve made a commitment that they can’t just walk away from,” Hamilton said. “But I have a hard time believing they will be able to hold to that path as the public continues to be exposed to the hazards of radiation and the limits of this technology. . . . You only think nuclear is a good idea if you really don’t think about the risks.”

Staff writer David Fahrenthold contributed to this report.