Congressional efforts to renew the "Superfund" toxic-waste cleanup law exploded into an intraparty battle yesterday as a House subcommittee rebuffed its chairman and approved a bill that includes many weakening amendments supported by the Reagan administration.

By back-to-back votes of 13 to 5, the House Energy and Commerce panel jettisoned a bill sponsored by subcommittee Chairman James J. Florio (D-N.J.) and approved a measure offered by Rep. Dennis E. Eckart (D-Ohio). Eckart's bill had the support of Rep. John D. Dingell (D-Mich.), chairman of the full committee, and most of the panel's Republican members.

Although both bills call for a $10 billion cleanup effort over five years, Florio denounced Eckart's version as toothless legislation that will give the Environmental Protection Agency "the ultimate excuse for doing nothing."

"A number of people don't know what was in the bill they voted for," said Florio, who adjourned the stormy session immediately after Eckart's bill was approved.

An impromptu news conference by Eckart and his supporters was halted when subcommittee aides doused the lights in the hearing room. In an interview later, Eckart said he had offered the substitute bill because Florio's version "would have required radical surgery" to win approval in the industry-oriented subcommittee.

"I wanted to get the process moving forward," he said. "I didn't gavel the meeting to a close. I fully intended to support other amendments that would be offered." Eckart characterized his bill as a compromise designed to "get a commitment from members not otherwise amenable to a $10 billion bill."

But some of Eckart's Democratic colleagues attacked the measure with venom, suggesting a rocky road ahead for legislation to renew Superfund, which will expire this year unless Congress acts.

"Those who are doing the mugging may like to pretend they're helping us across the street," said Rep. Gerry E. Sikorski (D-Minn.), a cosponsor of Florio's bill. "This so-called compromise doesn't save anything. It guts a strong Superfund bill."

Florio said the defeat of his bill, which was closely modeled on a version that passed the House overwhelmingly last year, raises the possibility that Superfund supporters might have to settle for a one-year extension of the law rather than a five-year renewal.

Eckart's version makes several major changes in Florio's legislation, including removing a rigid timetable for cleanups, omitting a provision that allows citizens to take court action against polluters, and deleting language on liability standards for toxic-waste sites.

Eckart's bill also would allow the federal government to preempt state right-to-know laws, under which citizens can demand information on hazardous substances in their communities. According to Florio, it also would "provide for the self-destruction" of Superfund by cutting off cleanup funds in two years to any state lacking a hazardous-waste disposal facility.

The administration has supported such a fund cutoff, but Eckart said that the provision was deleted from the bill he introduced yesterday. "There was an agreement to remove it," he said. "That's not an issue."

Eckart said he omitted explicit language on liability for toxic dumps because he feared an industry-inspired attempt to water down Superfund's strict liability provisions. Industry and insurance groups strongly oppose the standards, which can make any single contributor of toxic waste liable for cleaning up an entire site.

Eckart also said he would work to strengthen other aspects of the bill, including citizens' suits and right-to-know provisions.

"It's an attempt to put wings on a sow," Sikorski responded.

EPA officials praised Eckart's measure as "a step in the right direction," but said it still contained too much money and attempted to address too many toxic problems. The administration wants no more than $5.3 billion for Superfund over the next five years.

"We'd like to see them further limit the scope," said one EPA official. "They've done some."

Environmental lobbyists, meanwhile, condemned the bill. "They put committee politics ahead of public health," said Leslie Dach of the National Audubon Society. "Eckart can't support what he voted for today."