WASHINGTON – Nuclear energy could be making a comeback thanks to ... Democrats?

Several candidates vying for the party's presidential nomination in 2020 are promoting or have shown openness to expanding "next-generation" nuclear power as part of the arsenal of options to aggressively address the effects of climate change.

Sen. Cory Booker, D-N.J., Rep. John Delaney, D-Md., and Sen. Amy Klobuchar, D-Minn. are backing expansion of modern nuclear energythat would have to meet tougher safety standards. Several other White House candidates, including former Colorado Gov. John Hickenlooper, Rep. Tim Ryan, D-Ohio, and Sen. Elizabeth Warren, D-Mass., have signaled they are open to the idea of nuclear power but have not pushed it as part of their agendas.

Even the Green New Deal, New York Democrat Rep. Alexandria Ocasio-Cortez's sweeping social justice proposal to combat climate change, doesn't rule out nuclear power expansion despite a draft recommendation initially calling for the decommissioning of all of the nation's nuclear reactors within a decade.

“It’s imperative for the United States to lead the way on tackling the world's climate crisis, and that must include the development of clean and innovative technologies like next generation nuclear energy,” Booker said this year when joining a bipartisan group of colleagues to re-introduce the Nuclear Energy Leadership Act.

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It seems a strange turn for a party that not long ago fiercely opposed the industry.

Former Vice President Al Gore, known for his environmental activism, opposed expansion of nuclear power when he was the 2000 Democratic presidential nominee. Democratic megadonor Tom Steyer, who has funded climate change initiatives at the ballot box and flirted with a run for president, advocates for renewable fuels and improved energy storage, but not nuclear. And Sen. Bernie Sanders, I-Vt., a leading candidate for the 2020 presidential nomination, opposes renewing existing licenses because "the toxic waste byproducts of nuclear plants are not worth the risks of the technology’s benefit."

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But the call for rapid decarbonization of the atmosphere to remedy a warming planet means nuclear power is at least getting a second look.

"It's a pragmatic position," said Sam Ori, executive director at the Energy Policy Institute at the University of Chicago. "I'm not surprised that there's a set of national policymakers who are taking progressive positions on dealing with climate change and including nuclear in that."

The support for nuclear power isn't often loud or well-laid-out publicly. Instead, it's sold in more subtle language as part of an "all-of-the-above" strategy to replace the fossil fuel sources warming the planet.

Washington Gov. Jay Inslee, who has made his presidential campaign chiefly about solving climate change, said he is focusing "first and foremost" on expanding renewable alternatives such as wind and solar, improved efficiency, a smarter power grid and energy storage technologies.

But "we should continue to explore next-generation advanced nuclear technologies," the governor said in a statement provided to USA TODAY, adding that it would have to be safe, competitively priced and come with a plan for storing waste.

Not every candidate seeking the Democratic presidential nomination is a fan, mirroring a similar divide in the environmental community.

Sen. Kamala Harris, D-Calif., Sen. Kirsten Gillibrand, D-N.Y., and Rep. Tulsi Gabbard, D-Hi., are among those who oppose including nuclear technology on the clean energy menu. Gabbard has criticized the Green New Deal for being too "vague" because it does not ban nuclear power.

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The state of nuclear power

Nuclear power, generated by 98 commercial reactors at 60 plants scattered across 30 states, provides nearly 20% of the nation's electricity, according to government figures. That makes nuclear the largest single supplier of carbon-free energy in the U.S.

But economic factors, mainly from the production of cheap natural gas and increasingly affordable renewable sources, are slowly driving nuclear power out of business. In addition, diminished demand has hurt profitability, as have rising costs to operate them, analysts say.

President Donald Trump, a climate change skeptic whose administration has championed fossil fuels such as oil and coal, signed legislation in 2018 to expand the nuclear industry.

"A complete review of U.S. nuclear energy policy will help us find new ways to revitalize this crucial energy resource," he said in a speech at the Department of Energy nearly two years ago.

Only one new nuclear power plant has come online in the United States since 2010: The Watts Bar Unit 2 in Tennessee, according to the U.S. Energy Information Administration. Two more reactors are under construction in Georgia, according to the Nuclear Regulatory Commission.

But six reactors at five plants have been mothballed since 2013, seven others at five more plants are slated to retire over the next seven years, and another five reactors at four more plants are expected to close in the next few years if they do not receive new financial support, according to a report from the Union of Concerned Scientists.

The Oyster Creek reactor in New Jersey produced its last megawatt of energy in September. And two other plants – Pilgrim Nuclear Power Station in Massachusetts and Three Mile Island Nuclear Station (Unit 1) in Pennsylvania – are expected to retire later this year.

Safety remains a major concern as well, 40 years after Three Mile Island's Unit 2 suffered a partial meltdown in what remains the nation's worst commercial nuclear accident. The threat of a terrorist attack and the potential damage from a major hurricane (nuclear plants sit on or near bodies of water) have added to the angst.

And there's the question of finding a permanent repository for nuclear waste, a question that has bedeviled for years.

Spent nuclear fuel is now being stored in pools or in concrete and steel “dry casks” at every operating reactor site, as well as the sites of permanently shut down reactors. All those sites have, and will continue to have, adequate storage for their spent fuel, NRC spokesman Scott Burnell wrote in an email.

But storage specifically is one reason Sanders and others have called for a moratorium on nuclear power plant license renewals.

Ori, the University of Chicago analyst, said the center-left – which advocates considering nuclear energy – remains a powerful voice in the Democratic Party.

"But that doesn't mean eventually that this policy isn't going to run into the strong resistance to nuclear from the farther left of the party and from the dominant voices in the climate policy movement," he said. "Eventually those things are going to collide."