Four Arizona Democrats have signed on as co-sponsors of ambitious legislation that would commit the United States to achieve a 100% clean energy economy by 2050.

The bill would require economy-wide net-zero greenhouse gas emissions and would also direct federal agencies to draft plans to clamp down on emissions that contribute to climate change. The Arizona Democrats are among the more than 150 Democratic co-sponsors to the bill, which was introduced this week by Rep. Don McEachin (D-Va.) and has the backing of national environmental groups.