A House energy subcommitte voted yesterday to give the president standby authority to institute gasoline rationing.

The move is the first step toward reversing action taken by the House two months ago, when it rejected a standby gas rationing proposal.

Long gas lines, spreading shortages and growing public concern over the energy crisis have caused Democratic House leaders to reintroduce the proposal and to predict it will win House approval, this time.

The proposal, adopted 14 to 7 by the House Commerce energy subcommittee. lacks one of the key elements that led to the defeat of the last plan - that the president come up with a detailed gas rationing plan at the same time he asks for the standby authority.

The amendment by Rep. Timothy E. Wirth (D-Colo.) adopted yesterday would give the president standby authority, but would demand no specific rationing plan until 60 days before the date the president says he wants to put rationing into effect. Once it gets the plan, Congress would have 15 days to review it, and either house could veto it.

The rationing proposal was adopted only after its backers agreed to a compromise by Rep. Phil Gramm (D-Tex.) that would prevent the president from imposing gasoline rationing unless there was a 20 percent shortage over the preceding year's oil supplies, or such a shortage was anticipated.

Gramm said the purpose of his amendment was to ensure that "rationing is not used in a capricious way, that the situation is so catastrophic no alternatives to rationing" exist.

However, Rep. Albert Gore (D-Tenn.) said there was a legal loophole that would allow the president to institute rationing if an International Energy Agency allocation plan were triggered. A 7 percent worldwide shortage could trigger such a plan. The worldwide shortfall because of the Iranian shutdown last winter was 5 percent.

The IES agreement negotiated by former secretary of state Henry A. Kissinger is designed to serve as an insurance policy for the United States and the 19 other IEA members in the event of another Arab oil embargo. oil in the event of another Arab oil embargo. The member nations agreed to share oil in the event of severe shortfall.

Gramm then had language adopted saying there should be a serious shortage before the president could declare gas rationing to meet U.S. obligations to the IEA, but subcommittee members made it clear that his language did not close the loophole and Gramm did not contradict them.

Gramm's amendments also would require that all states share supplies equally in the event of a severe shortfall.

Wirth said the House has "learned some lessons" since the defeat of the last plan, namely that the legislators, subject to all the competing interests, connot come up with a rationing plan.

This method gives the administration the authority to "sort it all out."

Republicans on the panel voted against the plan, and Rep. Philip Sharp (D-Ind.) said its passage was not assured.

The proposal was an amendment to a bill to give broad powers to states and the president to come up with the conservation plans other than rationing. The president sets conservation targets and the governors devise plans to meet those targets.

If the president determines states aren't meeting the targets, he could impose a federal plan which might include automobile stickers setting aside one day of the week on which a car cannot be driven.

Rep. David Stockman (D-Mich.) said the conservation bill gives some of the "most wide open, sweeping grants of power ever granted by the Congress."