This post may contain affiliate links; please read our advertiser disclosure for more information.More than 1,700 merchants including giants such as Walmart and Target are urging lawmakers to pass legislation that would diversify the credit card processing market.Currently most credit card transactions are run through Visa and Mastercard. A bill introduced in July, would give merchants the right to route many credit-card payments over other networks other than Visa and Mastercard.In a letter this week to all members of Congress, the merchants said the proposed legislation would increase competition, leading to a reduction in credit card processing fees, which are some of the highest in the developed world. “In 2021 alone, U.S. merchants and consumers paid nearly $138 billion in card fees,” the letter says.Sen. Richard Durbin, who is one of the sponsors of the bill, championed a similar rule for debit cards more than a decade ago. The Durbin amendment, part of the 2010 Dodd-Frank law, requires banks to enable at least two unaffiliated debit networks on each card.The new bill would direct the Federal Reserve to require large banks that issue credit cards to enable at least one alternate network, other than Visa or Mastercard. The rule would apply on Visa or Mastercard credit cards that are issued by banks with more than $100 billion in assets.Currently, most domestic credit card issuers pair up with one of the two major networks, Visa or Mastercard. The network is typically listed on the front or back of the card, where most likely you will find the Visa or Mastercard logo. Some networks like Discover and American Express issue their own cards as well.When a shopper uses a credit card, the merchant pays a variety of fees, including an interchange fee that is set by the network and collected by the card issuer. Visa and Mastercard together handled roughly 77% of all general-purpose credit-card spending last year.Lawmakers are expected to receive another letter Wednesday signed by more than 150 merchant trade groups, WSJ reports.Disclosure: Miles to Memories has partnered with CardRatings for our coverage of credit card products. Miles to Memories and CardRatings may receive a commission from card issuers. Opinions, reviews, analyses & recommendations are the author’s alone, and have not been reviewed, endorsed or approved by any of these entities.Featured: Capital One Venture – Increased 75K Welcome Offer! Capital One Venture has an increased offer right now. For a limited time you can earn 75,000 Miles after $4K spend in the first 3 months of having the card. Venture earns 2X Miles on all purchases plus 5X with Capital One travel. Points can be used for a variety of things including cash back and transferring to travel partners.