As more marijuana shops take root in states that have legalized the drug, they're struggling with a lack of access to the kind of routine banking services other businesses take for granted.
Democratic Massachusetts U.S. Sen. Elizabeth Warren is leading a new effort to make sure vendors working with legal marijuana businesses don't have their banking services taken away.
The vendors include chemists who test marijuana for harmful substances and firms that provide security for pot shops.
It's part of a wider effort by Warren and others to bring the burgeoning $7 billion marijuana industry in from a fiscal limbo she says forces many marijuana shops to rely solely on cash.
Warren says helping marijuana-based businesses move away from a cash-only model also will help ensure they're paying their taxes.