Sen. Patrick Leahy (D-VT) today called on Comcast to make a long-term pledge that it won’t charge content providers for faster access to its subscribers.

Comcast already agreed to follow network neutrality provisions until September 2018 as part of its 2011 purchase of NBCUniversal. While the agreement with the US government doesn’t specifically prevent Comcast from signing paid prioritization deals, the company has said it has no plans to do so. Comcast has been touting its net neutrality commitments while making the case that it should be allowed to purchase Time Warner Cable, the second biggest cable company in the US after itself.

Leahy, chairman of the Senate Judiciary Committee, wrote a letter to Comcast Executive VP David Cohen today, saying he worries about “the risk of paid prioritization agreements through which websites could be charged for priority access over the Internet.” Leahy wants “meaningful pledges from our Nation’s broadband providers that they share the American public’s commitment to an Internet that remains open and equally accessible to all.”