WASHINGTON — Leaders of a Senate committee are set to propose legislation that would assign oversight of the two largest cryptocurrencies, bitcoin and ether, to the federal agency that regulates milk futures and interest-rate swaps.

Senate Agriculture Committee Chairwoman Debbie Stabenow and top-ranking Republican John Boozman of Arkansas, are planning to introduce a bill on 3 August that would empower the Commodity Futures Trading Commission to regulate spot markets for digital commodities, a newly created asset class. Currently, the CFTC has authority to police derivatives, such as futures and swaps, rather than underlying commodities.