Harry Reid wants the Federal Communications Commission to know he'll be on the agency's side in a political battle with Republicans.
In a letter to liberal advocacy groups, the Senate majority leader vowed to "lead the fight" to defend net-neutrality regulations "against the inevitable Republican attack."
The Senate's top Democrat said the regulations should give consumers "access to the lawful content they want when they want it" and should "ensure that priority arrangements that harm consumers are prohibited."
Reid's letter could reassure FCC Chairman Tom Wheeler that he has the political support he needs to ignore the Republican outcry and enact strong net-neutrality regulations.
The FCC first enacted net-neutrality rules in 2010 that barred Internet service providers from blocking websites or "unreasonably" discriminating against any traffic. A federal court struck those rules down earlier this year, and Wheeler is now trying to rework the regulations in a way that can survive court challenges.
His proposal has sparked a massive backlash because it could allow Internet providers to charge websites for faster service as long as the agreements are "commercially reasonable."
Liberal groups and some Democratic lawmakers have urged Wheeler to regulate Internet service providers under the same authority that the FCC uses for telephone companies. Reclassifying Internet providers as utilities under Title II of the Communications Act would give the FCC sweeping power to enact tough net-neutrality rules, but it would prompt a major battle with industry groups and congressional Republicans.