"Although many states have established protections for those who borrow from payday lenders — such as imposing licensing requirements and limiting the amount of fees and interest that can be charged on these loans — many of these shadow lenders hide behind anonymously registered websites and 'lead generators' to subvert state level lending laws," they wrote. "Banks should take every available step to prevent payday lenders from harming their own customers."

Cummings and Bonamici have introduced the SAFE Lending Act, H.R. 990, which is aimed at giving people more control over bank withdrawals from payday lenders and tightening regulations on these lenders.

But because that bill has not moved in the House, they asked banks to voluntarily take steps to provide these protections. For example, they noted that JPMorgan Chase has said it would reduce fees associated with overdrafts caused by withdrawals from payday lenders, and would ensure bank employees honor customer requests to block payday withdrawals.

"Although these are serious steps to help combat the abuses of payday lenders, all banks can do much more to protect hardworking Americans," they wrote.

In addition to JPMorgan Chase, the letter was sent to the CEOs of Bank of America, Citigroup, Wells Fargo and U.S. Bancorp.