The chairman of the Federal Communications Commission plans to announce Wednesday a controversial proposal that would prohibit Internet providers from favoring or discriminating against any traffic that goes over their networks.

He would do so, however, without resorting to the more drastic step of changing the way the FCC regulates broadband providers, a move that would have more clearly asserted the government's authority over Internet access.

In a statement provided to reporters in advance of Wednesday's announcement, FCC Chairman Julius Genachowski said he thinks he has "a sound legal basis" to pursue so-called net-neutrality rules that would prevent companies such as Verizon, Comcast and AT&T from blocking or serving up some Web sites faster and at better quality than others.

Last summer, Genachowski said he would move to reclassify broadband as something akin to more heavily regulated telephone service, after a federal appeals court threw the government's position as Web access regulator into question. The court said in April that the FCC had no legal authority to sanction Comcast for blocking files shared through the BitTorrent application.

Broadband companies strongly resisted being reclassified, and now Genachowski has shifted his approach.

"Informed by the staff's additional legal analysis and the extensive comments on this issue over the past year, the proposal is grounded in a variety of provisions of the communications laws, but would not reclassify broadband," Genachowski said.

Telecom lawyers and public interest groups have argued that without redefining its role over Internet service providers, the FCC's ability to carry out broadband rules is weakened. That suggests that the proposal Genachowski plans to announce Wednesday could still wind up being challenged in courts.

Genachowski's proposal also goes against warnings by emboldened Republican lawmakers who have criticized such rules as anti-business.

The proposal will be introduced for a vote before the five-member commission on Dec. 21.

But trying to make good on a promise for such rules made more than a year ago, Genachowski's proposal appears to strike a compromise between the interests of big network giants such as Verizon Communications and Web giants such as Google and Amazon. The Web companies have urged the FCC to oversee network operators so they don't favor some sites and applications - including their own and those of partners - over others.

The proposal bars the operators of broadband lines into homes from blocking Web sites, applications or any devices that attach to their networks. It would also prevent carriers from "unreasonable discrimination" that would, for example, serve up Comcast's Internet video service Xfinity faster and at better quality than that of rival Netflix.

For wireless networks, the rules are weaker. Mobile carriers such as Sprint Nextel, AT&T and T-Mobile would be prohibited from blocking competing voice and video applications such as Skype, Google Voice or Netflix. But wireless providers wouldn't have the same rules against prioritizing certain applications and sites on their networks like cable and telecom firms.

"Mobile broadband is at an earlier stage of development than fixed broadband, and is evolving rapidly," Genachowski said.