The Carter administration amended its standby gasoline rationing plan again yesterday to save it from apparent defeat in the Senate.

The hasty revision came after the Senate Energy Commitee earlier in the day rejected an already amended version of the rationing plan.

The committee then approved the new version late in the afternoon, and committee Chairman Henry M. Jackson (D-Wash.) predicted that it would pass the Senate today. If it does, the House is expected to take it up Thursday.

Before the twice-amended plan was approved by Jackson's committee, the White House issued a strong warning that rejection of the plan by Congress would leave the American people "in a defenseless position should some serious interruption of [oil] supply develop."

Presidential press secretary Jody Powell also predicted further worsening of gasoline shortages around the country and said the problem cannot be solved simply by increasing refinery production of gasoline because the nation's crude oil stocks are near a perilously low level.

In a defense of President Carter's decision to order increased production of home heating oil and diesel fuel for use on farms, Powell said the limited supply of crude oil to refine into different petroleum products leaves the nation with a choice between ample gasoline supplies and "being cold in the winter or not having enough food."

Under the third version of the rationing plan submitted by Carter for congressional approval, if rationing were put into effect, coupons would be distributed to the states solely on the basis of consumption of gas in each state during the previous year.

This was a reversal of the original formula to distribute coupons on the basis of the number of registered vehicles within a state regardless of distance driven. It was a victory for big rural states, where people must drive longer distances to work or market.

The original plan had been approved by the Senate Energy Committee, 9 to 8, with the undertstanding by some members that the administration would see to it that the big states would not suffer.

On Monday, in an effort to shore up the shaky plan, the administration sent up an amendment with a compromise formula, distributing half the coupons on the basis of registered vehicles and half on the historical use of gas. Senate Majority Leader Robert C. Byrd (D-W.Va.) said he believed this made the plan "winnable."

But yesterday morning the Energy Committee struck it down, largely at the persuasion of Sen. J. Bennett Johnston (D-La), who said he thought the administration had promised more than 50-50 for historical, from which his state would benefit.

The committee rejected the administration amendment, 12 to 6, and then voted 15 to 3 to send it to the Senate with a recommendation that it be voted down. At Johnston's request, the committee also withdrew its endorsement of the original plan. Johnston's switch to the opposition made the difference.

With the Energy Committee solidly against it, Jackson predicted that the Senate would reject the amendment plan. Byrd expressed surprise and agreement that the plan was in trouble. They urged the administration to come up with a new plan, which it did at 4 p.m. The Energy Committee then appoved it 9 to 7. Congress must approve the standby plan this week of it will die.

Earlier yesterday, the president met with congressional leaders and told them, according to a senior White House official that he would accept legilsation extending price controls on domestic oil beyond 1981 only if Congress also enacted measures that would reduce U.s. energy consumption, lessen the country's dependence on imported oil and provide additional funds to develop alternative energy sources.

"Obviously, everyone needs to understand that pursuing an extension of controls alone is not a responsible policy, but is a non-answer to our problem," the official quoted Carter as telling the congressional leaders.

The president's message to the congressional leaders was clearly meant to counteract the impact of his statement ast week at a news conference in Des Moines, where he said he would not veto legislation extending price controls but predicted that Congress would never enact such a measure.

At the White House, Powell told reporters the country currently has stocks of 319 million barrels of crude oil from which gasoline and other petroleum products are refined. He described 310 million barrels as the "minimal safe level" to protect the nation against disruptions in supply, and said the crude oil stocks should be at 340 million or 350 million barrels.

Powell blamed the low level of crude oil supplies on the cutback in production by Iran. He said U.S. crude stocks are beginning to climb, but argued that until they reach higher levels first priorities in refining will have to be given to the production of heating oil and fuel for agriculture rather than gasoline.

According to figures supplied by the Energy Department, U.S. crude oilstocks were below the level of 310 million barrels at the end of January and February. In the last two months, the stocks have fluctuated between 307 million barrels and 326 million barrels, and stood at 319 million barrels at the end of April.

Powell appeared a second time before reporters yesterday to issue his warning about the standby rationing plan. He said it was stalled by "a squabble not over fairness and equity . . . but over the desire or desires of this or that particular interest, this or that particular state or region or area within a state for a few gallons less for somebody else."

If approved, the rationing plan would go into effect when the president decided that gasoline shortages had created an emergency. But it could be stopped by a veto of either house of Congress. Than plan has no precise figure for what constitutes an emergency. Estimates range upward from a gas shortage of 15 percent below normal.

The plan would limit the number of cars eligible for coupons to three per household unless hardship could be proved. CAPTION: Picture, Sens. Johnston and Jackson confer on Carter's twice-amended gas rationing plan.By James K. W. Atherton-The Washington Post