WASHINGTON -- Republicans trying to finish the first major energy legislation in a decade continued to hit obstacles in recent talks and postponed a scheduled meeting that would have allowed a House-Senate negotiating committee to approve the measure.

House Republicans had hoped to bring the bill to the floor earlier, but that timetable was in jeopardy after House and Senate Republicans writing the measure were unable to make public a final proposal by Sunday evening. Senate Democrats have requested at least 24 hours to review the measure before a final meeting of the conference committee.

Congressional officials said negotiators had resolved the chief policy issues like new standards for the electric utility industry, initiatives to spur oil and gas production and a plan to increase ethanol in gasoline. But lawmakers had not agreed on the amount and type of tax incentives, issues that House and Senate tax writers negotiate.

Democrats, who say that for the most part they have been cut out of the negotiations, called on Republicans to make public the agreements that have been reached so they could begin to digest the proposal.

But Congressional aides said Republicans were reluctant to do that without a completed agreement because it could provide opponents more opportunity to attack the measure while giving lawmakers time to push for adding proposals.

Meanwhile, new problems surfaced. A bipartisan group of 29 senators wrote to the conference committee to reinforce their support for ethanol provisions passed by the Senate. Environmental groups raised concern over a last-minute plan to relax some air-pollution requirements. And in a proposal covering producers of a gasoline additive blamed for contaminating groundwater, an agreement giving them immunity retroactive to Oct. 1 in product liability cases came under scrutiny because of lawsuits in the last few weeks.

"It is another reason to vote against it," said Senator Judd Gregg, Republican of New Hampshire, a state where lawsuits have been recently filed.

Industry officials said they did not believe the suits would be affected.