WASHINGTON - The head of the Federal Communications Commission has enough support to pass controversial new rules that will prohibit phone and cable companies from discriminating against or favoring Internet traffic over their broadband networks.

Among the cable companies affected would be Comcast Corp. of Philadelphia.

More than a year after FCC Chairman Julius Genachowski pledged to enact so-called network neutrality regulations, the agency is expected to adopt those rules at a meeting Tuesday.

Although the two Republicans on the five-member commission firmly oppose the plan, Genachowski's two Democratic colleagues have said they would vote to let the proposal pass. Those Democrats, Mignon Clyburn and Michael Copps, have said they still have reservations about the rules, however.

"The item we will vote on tomorrow is not the one I would have crafted," Copps said. "I believe we have been able to make the current iteration better."

The rules "could represent an important milestone in the ongoing struggle to safeguard the awesome opportunity-creating power of the open Internet," Copps said.