The unfolding nuclear disaster in Japan at reactors damaged by a massive earthquake and tsunami has led some lawmakers to call for putting the "brakes" on US nuclear development.
"I've been a big supporter of nuclear power because it's domestic it's ours and it's clean," Senator Joseph Lieberman told the CBS News television program "Face The Nation" Sunday.
Nevertheless "I think we've got to ... quietly and quickly put the brakes on until we can absorb what has happened in Japan as a result of the earthquake and the tsunami," said Lieberman, who is chairman of the Senate Homeland Security Committee.
Experts must then "see what more, if anything, we can demand of the new power plants that are coming online."
President Barack Obama wants to increase nuclear power as part of a US effort to decrease the nation's dependence on coal and foreign oil. The administration has allocated US$18.5 billion in Department of Energy loan guarantees to spur nuclear development.
The White House stood by its policy Sunday, but sounded a note of caution.
"The president believes that meeting our energy needs means relying on a diverse set of energy sources that includes renewables like wind and solar, natural gas, clean coal and nuclear power," said White House spokesman Clark Stevens told The New York Times.
"Information is still coming in about the events unfolding in Japan, but the administration is committed to learning from them and ensuring that nuclear energy is produced safely and responsibly here in the US," the spokesman is quoted by the newspaper as saying.
US Representative Edward Markey, a nuclear power critic, called for a moratorium on building reactors in seismically active areas, according to The Times.
The disaster in Japan "serves to highlight both the fragility of nuclear power plants and the potential consequences associated with a radiological release caused by earthquake-related damage," Markey said in a statement.
Nuclear energy however still has supporters on Capitol Hill.
Senator Charles Schumer told NBC's "Meet the Press" on Sunday that the unrest in oil-rich Libya is evidence that "we do have to free ourselves" of dependence on foreign oil.
"Prices are up. Our economy is being hurt by it or could be hurt by it. So I'm still willing to look at nuclear. As I've always said it has to be done safely and carefully," the New York Democrat said.
Senate Minority Leader Mitch McConnell told the Fox News Sunday program that lawmakers shouldn't make snap judgments.
"I don't think right after a major environmental catastrophe is a very good time to be making American domestic policy," the powerful Republican said.
Friday's colossal 8.9 earthquake and subsequent tsunami, which sparked an emergency at two of Japan's nuclear power plants and could result in catastrophic meltdowns, has many US nuclear energy advocates thinking twice.
Part of a reactor at Japan's aging Fukushima No. 1 atomic plant blew up Saturday, a day after the biggest quake ever recorded in Japan unleashed a 10-meter (33-foot) tsunami.
Another explosion shook the quake-damaged power plant on Monday.
Excessive radiation levels were recorded at a second Japanese nuclear facility, Onagawa, on Sunday, although authorities insisted the facility's three reactor units were "under control."
"It is considered to be extremely unlikely but the (nuclear) station blackout has been one of the great concerns for decades," said Ken Bergeron, a physicist who has worked on nuclear reactor accident simulation.
Nuclear opponent Ira Helfand, board member of Physicians for Social Responsibility, said an overlooked threat to nuclear plants is terrorism.
"They are essentially weapons of mass destruction that we build ourselves and site next to our cities and thereby hold huge numbers of people hostage to acts of nature or occasionally perhaps acts of man that we cannot control," he said.