WASHINGTON (Reuters) - U.S. regulators on Thursday advanced a “net neutrality” proposal that would ban Internet providers from blocking or slowing down access to websites but may let them charge content companies for faster and more reliable delivery of their traffic to users.

For four months now, the public can weigh in on the rules proposed by the Federal Communications Commission (FCC) in what promises to be an intense tug-of-war between some tech companies and consumer advocates on one side and Republicans and broadband providers on the other, over the extent to which the agency can regulate Internet traffic.

Dozens protested the vote at the FCC on Thursday as many consumer advocates have rejected FCC Chairman Tom Wheeler’s proposal that may allow some “commercially reasonable” deals in which content companies could pay broadband providers to prioritize traffic on their networks.

Critics worry the rules would create “fast lanes” for companies that pay up and mean slower traffic for others. Wheeler pledged to use all of his powers to prevent “acts to divide the Internet between ‘haves’ and ‘have nots.’”

“I will not allow the national asset of an open Internet to be compromised,” Wheeler said. “The prospect of a gatekeeper choosing winners and losers on the Internet is unacceptable.”

Consumer advocates want the FCC to instead reclassify Internet providers as utilities, like telephone companies, rather than as the less-regulated information services they are now. Broadband companies and Republicans, both in Congress and at the FCC, vehemently oppose the plan.

The advanced proposal seeks comment on benefits of reclassification, which critics say would throw the industry into legal limbo, discourage investment in network infrastructure and still not prevent pay-for-priority deals.

Wheeler’s two fellow Democrats at the FCC expressed misgivings about his proposal, with Commissioner Jessica Rosenworcel saying the FCC moved “too fast to be fair.” But she and Mignon Clyburn concurred with Wheeler for a 3-2 vote to begin the process of collecting public comment on the proposal.

“The real call to action begins after the vote today,” Clyburn said. “You have the ear of the entire FCC. The eyes of the world are on all of us.”

The FCC’s move comes after a U.S. appeals court rejected its earlier net neutrality rules, which said pay-for-priority deals “would raise significant cause for concern.” To comply with the court, the new proposal suggests some pay-for-priority deals may be allowed, but also asks whether “some or all” such deals can be banned.

“The FCC’s efforts were dealt a real challenge by the Court of Appeals in January, but Chairman Wheeler has said his goal is to preserve an open Internet, and we are pleased to see that he is keeping all options on the table,” the White House said in a statement, adding they will watch the independent agency’s work “in hopes that the final rule stays true to the spirit of net neutrality.”

The FCC’s vote was cautiously welcomed by both broadband providers and consumer interest and technology groups as each side hopes the ultimate rules lean their way.

“Nothing should be taken off the table as this discussion evolves,” Michael Beckerman, chief executive officer of the Internet Association that represents companies including Google Inc and Facebook Inc, said in a statement, adding that his group will “advocate for the FCC to use its full legal authority to enforce rules that lead to an open Internet.”