Senator Bernie Sanders and Representative Greg Casar (D-TX) have announced the Ban Artificial Superintelligence Act, which would "permanently ban the development and deployment of superintelligent AI and temporarily pause advanced AI development until a federal regulator has established safety rules. It would also direct the U.S. to pursue international agreements to prevent superintelligence from being developed anywhere in the world."
So far this is just an announcement, so fulltext of the bill is not available, but there is a press release and one-page summary out.
Confirmed, from the Washington Post in a brief interview with Conner Leahy:
"ControlAI, a nonprofit devoted to banning superintelligence, said it’s been working closely with Casar and Sanders’s teams on the bill."