Elizabeth Warren would keep existing nuclear plants online to combat climate change, she said at Thursday night's presidential primary debate, marking a shift in her position on an issue that has divided the Democratic field.

"We have to stop putting more carbon in the air. That means we need to keep some of our nuclear in place," Warren said.

Warren said, though, that she would not "build more nuclear" plants.

In September, Warren had said she opposed the building of new nuclear plants and would also work to phase out existing nuclear power from the energy mix.

"In my administration, we won't be building new nuclear plants," Warren said then at a CNN climate change town hall. "We will start weaning ourselves off nuclear and replace it with renewables."

The Democratic field has split on how to handle nuclear power, which provides twice as much carbon-free power in the United States than renewables.

Warren's liberal rival Bernie Sanders is perhaps the most skeptical of nuclear, citing concerns about storing nuclear waste, and the high cost of building new plants, in opposing it.

Sanders wants to impose a moratorium on license renewals for existing power plants, along with stopping the building of new plants.

Tom Steyer, the billionaire environmentalist, seemed to echo that position at Thursday night's debate, saying nuclear costs too much and presents too many risks.

"We have the technology we need: It's called wind and solar and batteries," Steyer said.

Rival candidates Cory Booker and Andrew Yang argue existing nuclear plants, along with new small modular reactors, are needed to combat climate change.