WASHINGTON — The Senate voted to keep in place federal rules aimed at preserving open Internet access for online users, but hurdles still loom for the controversial policy.

The so-called net neutrality regulations, enacted last year by the Federal Communications Commission, face a legal challenge from Verizon Communications Inc. and other opponents in a court that overturned the agency's last attempt to deal with the issue.

"Net neutrality lives or dies depending on what the court does," said Jeffrey Silva, a telecommunications analyst with Medley Global Advisors.

And even if the U.S. Court of Appeals for the District of Columbia upheld the regulations, they would probably get tossed should Republicans take control of the White House — and the FCC along with it — in next year's election.

Republicans have pushed hard to overturn the net neutrality rules, but a resolution to do so failed 52-46 on a party-line vote Thursday in the Democratic-controlled Senate. The White House this week had threatened to veto the bill if the Senate had approved it.

The vote ended a months-long attempt by opponents to wipe out the rules. In April, the Republican-controlled House voted 240-179 in favor of a similar resolution of disapproval.

An FCC spokesman called Thursday's vote "a win for consumers and businesses."

Sen. John F. Kerry, D-Mass., who backed the new rules, said supporters must keep fighting "because we know this isn't the last we've heard of the assault on net neutrality."

"Net neutrality is not about a government takeover of the Internet, and it is not about changing anything," said Sen. Al Franken, D-Minn. "Net neutrality and the rules the FCC passed are about keeping the Internet the way it is today and the way it has always been."

Republicans and many telecommunications companies have opposed the FCC's rules. GOP members argued that the FCC overstepped its authority and that regulation of the Internet would stifle its growth and curtail job opportunities.

"Over the past 20 years, the Internet has grown and flourished without burdensome regulations from Washington," said Sen. Kay Bailey Hutchison, R-Texas, who led the push in the Senate to overturn the rules.

Public interest groups and major online companies such as Google Inc. have worried for years that Internet service providers such as Verizon, Time Warner Cable Inc. and AT&T Inc. might charge premiums for faster speeds or might try to slow down access to online services, such as Netflix or Skype, that compete with their own offerings.

In 2008, the FCC ruled that cable giant Comcast Corp. discriminated against legal Internet content when it blocked some of its customers from using BitTorrent Inc.'s video downloading technology.

Comcast challenged the ruling, and the federal appeals court tossed out the FCC's decision, finding that the agency lacked the specific authority from Congress to regulate a cable company's Internet traffic.

President Barack Obama, an early supporter of net neutrality regulations as a senator, made the issue part of his 2008 campaign. Under his appointed chairman, Julius Genachowski, the FCC worked to craft a policy on Internet traffic that would withstand a legal challenge.

In December, the Democratic-controlled FCC voted 3-2 along party lines to adopt regulations that prohibit telecommunications companies from favoring their online services over those of competitors.

The rules, which apply to wired and wireless services, forbid companies from blocking their customers' access to any legal content, applications or services.

The FCC also prohibited companies that provide land-line Internet service from "unreasonable discrimination" in their treatment of access to content and services. The tougher requirement was placed on wired services because there are fewer providers than in the wireless industry.

The agency's two Republicans at the time — Robert M. McDowell and Meredith Attwell Baker — said the FCC still was exceeding its authority. But some public interest groups also were not happy that the FCC didn't go further, arguing that wireless providers should face the same tough restrictions as wired ones.

In September, the advocacy group Free Press challenged the rules in federal court in Boston, arguing they were not tough enough to protect wireless customers. Still, Free Press opposed the congressional attempts to overturn the rules, calling it "an appalling legislative stunt."

"The fight for real net neutrality continues," said Craig Aaron, president of Free Press. He urged policymakers to strengthen the rules, rather than weaken them.

The group's legal challenge and several others, including Verizon's, were consolidated and sent to the District of Columbia appeals court, which has rejected many major FCC decisions in the past, analyst Silva said.

In the Comcast case, the court "could not find any legal standing for the FCC to exercise power over the Internet," he said. "At a minimum, those rules are vulnerable given the history of net neutrality in the same court."