U.S. regulators Thursday advanced a proposal to let Internet-service providers led by AT&T and Comcast charge Web companies such as Google and Facebook to provide fast lanes for their content.

Federal Communications Commission Chairman Tom Wheeler had enough reluctant support from his two fellow Democrats to win a 3-2 preliminary vote for his proposal, which advocacy groups and Internet companies said undermines the ideal of treating Web traffic equally.

Internet service providers like AT&T and Comcast may benefit by charging more to distribute Internet content, while Web companies that might have to pay, such as Google and Netflix, are at a disadvantage.

The vote opens a comment-and-review period intended to lead to a second vote and a final rule later this year. A court in January threw out open-Internet rules the FCC adopted in 2010.

"I will not allow the national asset of an open Internet to be compromised," Wheeler said. The debate before the agency "is not about whether the Internet must be open, but about how and when we will have rules in place," Wheeler said.

Democrat Jessica Rosenworcel, renewing criticism that Wheeler had rushed the proposal, voted to advance it Thursday after saying the chairman had "put all options on the table."

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Both Republicans voted against the proposal.

"Nothing less than the future of the Internet depends on how we resolve this disagreement," said Commissioner Ajit Pai, the agency's senior Republican. "A dispute this fundamental is not for us, five unelected individuals, to decide," he said, adding that it should be the job of Congress.

The commission's other Republican, Michael O'Rielly, said Internet neutrality "rests on a faulty foundation of make- believe statutory authority."

Wheeler revised the proposal May 12 to add consideration of tougher regulations, including potential rate controls, under the agency's review.

Verizon Communications will review the FCC proposal and be "constructively engaged in the months to come," Randal Milch, executive vice president for public policy and general counsel, said in an emailed statement.

Verizon wants to charge Web companies for access to subscribers, a lawyer for the carrier told judges during its lawsuit against the FCC's now-voided rules.

While Wheeler was able to win over Democrats on the panel, industry and public interest groups remain skeptical.

"This is an alarming day for anyone who treasures a free and open Internet," Michael Copps, a former Democratic FCC member advising the policy group Common Cause, said in an email. "Any proposal to allow fast lanes for the few is emphatically not net neutrality."

The proposal "still falls well short of real net neutrality rules," Michael Weinberg, vice president at the Washington-based policy group Public Knowledge, said in an email. "It would create a two-tier Internet where 'commercially reasonable' discrimination is allowed."

The National Cable and Telecommunications Association is opposed to efforts to reclassify broadband services under "the heavy-handed regulatory yoke," Michael Powell, the group's president and chief executive officer, said in an emailed statement.

"The Internet is a feat of human ingenuity that has thrived under a light regulatory touch that has attracted more than $1.3 trillion of private investment since 1996," Powell said. "We urge the FCC to continue on a responsible path that will continue to fuel the private network investment that is essential to the continued growth and health of the Internet."

Allowing fast traffic that "squeezes out" small providers is unacceptable and the agency's proposed rules seek to stop that from happening, Wheeler said.

"There is one Internet," Wheeler said.

Under his proposal, service providers may negotiate deals on a case-by-case basis with content makers such as Netflix and Amazon.com for preferential connections to consumers' TVs and computers.

Internet companies including Amazon, Netflix, Google and Facebook told the agency the plan represents a "grave threat" to an open Internet because it could let service providers discriminate against content providers. Artists signed onto a letter of protest, and protesters encamped outside the FCC.

Prior to the start of the meeting, three members of the audience stood up and started shouting and had to be escorted out of the room today.

Wheeler said the proposal offers a route to rules, ending a decade of debate, that takes heed of the U.S. court's objections and avoids further litigation.

Wheeler's proposal also invites the agency to consider tougher rules, drawing warnings from Republican members of Congress including House Speaker John Boehner who oppose such a step.

The tougher rules may lead to rate regulation, according to carriers including largest U.S. cable provider Comcast, biggest telephone company by revenue AT&T and No. 2 phone company Verizon.