Joe Biden said he would not ban the practice of fracking for natural gas, distancing himself from some of his Democratic rivals, but said he would evaluate existing fracking permits to determine their safety.

"We can pass national legislation, but I don't think we would get it done to say all fracking going on ends unless we can say there is some physical security need," Biden said Wednesday night at CNN's climate change town hall, in response to a question about banning fracking.

Biden, the former vice president running as a relative centrist, has joined most of the other Democrats in endorsing the goal of the United States reaching net-zero emissions by 2050, but has stopped short of calling for the end of fracking, as competitors such as Sens. Bernie Sanders and Kamala Harris have done.

Biden, however, has proposed banning new oil and gas drilling leases on federal lands, a position held by every other Democratic candidate.