BRUNSWICK, Maine (AP) Maine’s independent senator is joining a push to clamp down on Russia’s ability to sell gold reserves.

Sen. Angus King is working with Republican Sens. John Cornyn of Texas and Bill Hagerty of Tennessee, and Democratic Sen. Maggie Hassan of New Hampshire on the effort. King said Tuesday the Stop Russian GOLD Act would apply secondary sanctions to any American entities that knowingly transact with or transport gold from Russia’s central bank holdings.

King said the sanctions would also apply to U.S. entities that sell gold physically or electronically in Russia. King said Russia’s “massive gold supply is one of the few remaining assets that Putin can use to keep his country’s economy from falling even further.”

The senators said Russia has $130 billion in gold reserves. They said sanctioning the reserves would isolate Russia from the world’s economy.