Watchdog groups are urging Senate Commerce Chairman Daniel Inouye, D-Hawaii, and House Judiciary Chairman John Conyers, D-Mich., to convene January hearings on recent allegations of discriminatory online practices. The House Energy and Commerce Telecommunications and the Internet Subcommittee that Markey heads already plans to hold additional sessions on the topic next year.

The legislative push is being fueled by recent flare-ups over net neutrality involving AT&T, Comcast and Verizon Communications, sources said. They noted that the online activist group MoveOn.org is urging Markey to revive the issue so it resonates more loudly on the presidential campaign trail.

The leading Democratic presidential contenders -- Sen. Hillary Clinton,of New York, former Sen. John Edwards of North Carolina, Sen. Barack Obama of Illinois and New Mexico Gov. Bill Richardson -- all have endorsed tougher neutrality safeguards to prevent broadband operators from potentially acting as content gatekeepers.

Details of the Markey bill were sketchy, but sources said the measure may be an updated version of the 11-page bill he introduced in May 2006 when broader Republican-backed telecom legislation was pending. Various ideas are being bandied about for the new iteration, including the possibility of mandating nationwide field hearings on the subject.

In addition to MoveOn, advocacy groups such as Free Press and the Open Internet Coalition have been consulted on drafting the measure, sources said.

Mandatory net neutrality restrictions are strongly opposed by the telecom and cable industries, which have long maintained that regulations are unnecessary and could interfere with their ability to manage Internet traffic flow. "What we've said all along is that the FCC has the ability to deal with bad actors," AT&T spokeswoman Claudia Jones said.

The FCC already has voluntary neutrality guidelines in place for companies to follow and has a pending notice of inquiry exploring allegations of discriminatory practices by Internet providers. The agency imposed temporary neutrality restrictions on the approval of the AT&T, BellSouth merger. Those restrictions will expire in late 2008.

In January, Sens. Byron Dorgan, D-N.D., and Olympia Snowe, R-Maine, reintroduced legislation designed to ensure that the Internet remains open and accessible to all consumers and competitors. Markey has failed several times to pass neutrality bills and amendments, but sources noted that the environment is different now that Democrats are in charge and a major election is looming that could further alter the political landscape.