Sen. Chris Coons (D-Del.) is willing to trim the EPA’s authority to regulate greenhouse gases in exchange for a carbon tax, he said at a June 20 event.

Coons, who plans to introduce carbon tax legislation as early as next week, said the trade-off may be necessary to achieve significant greenhouse gas emissions in the near future.

Re-creating and implementing a policy like the Clean Power Plan, the Obama administration’s regulatory framework to limit carbon emissions from the electricity...