The House Ways and Means Committee, facing a series of critical decisions on President Carter's beleaguered tax package, has decided to defer further consideration of the tax bill for at least a week, Chairman Al Ullman (D-Ore.) said yesterday.

Although the move ostensibly is to give the House-Senate conference committee a chance to work on the energy bill, it will allow Ways and Means leaders more time to work out a compromise on the tax measure.

Ullman said he plans to confer informally with committee members this week to "develop some kind of consensus" on how much of the Carter tax proposal the Ways and Means panel will accept.

Ullman also is expected to consult with Vice President Mondale and Secretary of the Treasury W. Michael Blumenthal to coordinate the panel's actions with the White House. "I anticipate a whole series of meetings," Ullman said.

The week-long deferral effectively will postpone expected consideration of a proposal by Rep. Charles A. Vanik (D-Ohio) that would scrap the Carter package and merely extend the tax cuts enacted in 1977.

Although the Vanik proposal had been considered unlikely to pass at first, it has recieved increasing support as liberals on Ways and Means became disgusted with the votes on tax revision. Panel members also are concerned that too large a tax cut might fuel inflation.

The flurry of informal meetings this week marks a last-ditch effort to salvage the tax bill in the face of indications by the panel that the measure is in serious trouble. The committee has scrapped President Carter's proposed tax code revisions and may reduce the size of his tax cut package as well.

The administration also has been pressing to work out some sort of compromise. Top economic policy makers met for two hours yesterday to review the situation, and Carter is scheduled to confer this week with several groups of committee members, including Republicans.

Ullman said yesterday he expects no formal compromise to emerge but simply for the committee to decide what to do, with "some consultations" with the White House.

He said that if Carter does not like the bill the panel drafts, the administration still will be free to try to have it amended on the House floor or in the Senate. He said he thought Carter "understood" the situation.

One possibility may be to trim the size of the tax reductions from the $25 billion net cut Carter proposed to $20 billion or less, as has been suggested by G. William Miller, chairman of the Federal Reserve Board.

Ullman said on the "Issues and Answers" (ABC, WJLA) program yesterday that he personally would "generally approve of that recommendation now, and I think the President would accept it."

Carter angrily denounced such suggestions two weeks ago, but that presumably was before he became fully aware that the tax measure was in trouble. The president said last Thursday he was surprised to find his tax proposal encountering so much opposition.

The Ways and Means Committee is scheduled to meet this morning to hear testimony from a group of prominent economist on how large a tax cut is necessary. The session was planned earlier both to review the economic outlook and to cut into support for the Vanik proposal.

However, Ullman said there will be no formal markup sessions for the rest of the week. "Those of us on the committee are going to have to develop some kind of consensus," he said. "The burden is going to be on us to get together."