Presidential candidate Kamala Harris said Wednesday that she supports banning the technique of fracking for natural gas to combat climate change.

"There is no question I am in favor of banning fracking," Harris said during an all-night CNN town hall event focused on climate change.

Harris suggested she would start by taking executive action on "day one" to ban fracking on public lands and then move to have Congress pass legislation to extend the prohibition to private lands.

Harris' formal climate plan, published earlier Wednesday, does not explicitly call for Congress to ban fracking, as fellow candidate Sen. Bernie Sanders has promised.

Sanders ahead of the CNN town hall released a statement challenging other candidates to adopt his call to ban fracking for natural gas on public and private lands. "Any proposal to avert the climate crisis must include a full fracking ban," he said.