Washington ? New rules aimed at prohibiting broadband providers from becoming gatekeepers of Internet traffic now have just enough votes to pass the Federal Communications Commission today.

The rules would prohibit phone and cable companies from abusing their control over broadband connections to discriminate against rival content or services, such as Internet phone calls or online video, or play favorites with Web traffic.

FCC Chairman Julius Genachowski now has the three votes needed for approval, despite firm opposition from the two Republicans on the five-member commission. Genachowski’s two fellow Democrats said Monday they will vote for the rules, even though they consider them too weak.

The outcome caps a nearly-16-month push by Genachowski to pass “network neutrality” rules and marks a key turning point in a policy dispute that began more than five years ago.

“The open Internet is a crucial American marketplace, and I believe that it is appropriate for the FCC to safeguard it by adopting an order that will establish clear rules to protect consumers’ access,” Commissioner Mignon Clyburn, a Democrat, said in a statement.

Yet many supporters of network neutrality are disappointed. Clyburn and the other Democrat, Michael Copps, both said the rules are not as strong as they would like, even after Genachowski made some changes to address their concerns.

That sentiment was echoed by some public interest groups today.

“The actions by the Federal Communications Commission fall far short of what they could have been,” said Gigi Sohn, president of Public Knowledge. “Instead of strong, firm rules providing clear protections, the commission, created a vague and shifting landscape open to interpretation.”

A number of big Internet companies, including Netflix Inc., Skype and Amazon.com Inc., have previously expressed reservations about the proposal as well.

Meanwhile, even the weakened rules are likely to face intense scrutiny as soon as the Republicans take over the House next year.