WASHINGTON – U.S. telecom regulators are poised to approve rules on Tuesday designed to ensure an open Internet.

The rules aimed at safeguarding "network neutrality," the principle that Web traffic should be treated equally, are to be put to a vote at a meeting here of the five-member Federal Communications Commission (FCC).

They were ensured approval after two Democrats on the FCC said Monday that they would side with FCC chairman Julius Genachowski, another Democrat, when the rules come up for a vote.

"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," FCC commissioner Mignon Clyburn said in a statement.

"The Commission has worked tirelessly to offer a set of guidelines that, while not as strong as they could be, will nonetheless protect consumers as they explore, learn, and innovate online," Clyburn said.

The rules are a balancing act by the FCC between support for consumers and the cable and telephone companies that are the major Internet Service Providers in the United States.

Genachowski, in a speech earlier this month, said the rules would prevent broadband providers from abusing their position as the "gatekeepers to the Internet" by blocking lawful content, applications and services.

At the same time, the rules would give them the "meaningful flexibility to manage their networks," the FCC chairman said.

The rules, for example, would allow fixed broadband providers to charge consumers according to usage, a metered pricing practice already used by some wireless carriers.

Senior FCC officials said Monday the rules require robust transparency from fixed and mobile broadband providers and prohibit them from blocking any lawful content or applications.

The rules allow broadband providers to engage in reasonable network management but not to "unreasonably discriminate" against traffic on their networks, they said.

The FCC drafted the rules after suffering a legal setback in April when a court ruled that it had not been granted the authority by Congress to regulate the network management practices of Internet service providers.

Some Republican lawmakers in the US Congress have denounced the rules as unnecessary government regulation and their approval could pave the way for more legal battles.