Lawmakers embracing a transition to 100 percent renewable energy under a Green New Deal have largely left out mention of whether nuclear energy should be included in such a policy package. While Rep. Alexandria Ocasio-Cortez, one of the Green New Deal’s biggest proponents, said she hasn’t ruled out nuclear energy from the platform, other advocates on the left hold long-running concerns that appear to lessen nuclear’s chances of inclusion in the deal.

Rep. Chellie Pingree (D-Maine) is one of over 40 lawmakers who have issued their support for Green New Deal concepts championed by the freshman Democratic representative from New York, who has floated a draft resolution that calls on lawmakers to work toward supplying 100 percent of U.S. power demand from renewables, building a national smart grid and putting money toward a drawdown of greenhouse gases.

“I think on nuclear energy, we all have a general resistance to it,” Pingree said, because of the unsolved quandary of how to deal with nuclear waste, along with remaining environmental and safety issues. “We all think of Japan.”

For her part, Ocasio-Cortez is holding back from stating a firm position on including nuclear energy in a Green New Deal.

“It’s not something that we’ve just ruled out,” Ocasio-Cortez said Thursday.

Supporters of the initiative’s top goal, she said, is to reach zero percent carbon emissions. Debate over nuclear energy is ongoing, and “we’re monitoring that debate and seeing where we can land,” she added.