The odds that Congress will pass a tax-cut bill this year diminished considerably yesterday as two influential House members said they doubted there would be time to consider it until 1981 and Carter administration officials sent out signals they don't like the idea.

"I would love to see us do it," said Rep. Barber B. Conable Jr. (N.Y.), the ranking Republican on the House Ways and Means Committee, "but it would be very tough to get it through." Rep. Al Ullman (D-Ore.), the committee chairman, who lost his reelection race Tuesday, agreed with Conable.

The tax bill has been pushed back onto Congress' post-election agenda Thursday. Sen. Bob Dole (R-Kan.), trying to capitalize on President-elect Ronald Reagan's big victory, called for immediate passage of the $39 billion tax-cut bill already approved by the Senate Finance Committee. Dole will become chairman of the committee in 1981.

Reagan gave Dole some encouragement at his news conference last Thursday, saying it would be "just fine" with him if Congress enacted a tax bill this year.

But Carter administration officials said yesterday that Reagan's victory hasn't changed their view that enactment of a tax bill this year is a bad idea. h"They deserve a chance to put their program into effect," said one senior administration official, but he said that trying to push a bill through in a lame-duck session "isn't the way to do it."

"I suspect we would oppose it," the official said.

Administration officials said they didn't know whether President Carter, who earlier had urged delay, would veto a tax bill passed this year.

Ullman said he wouldn't stand in the way of the tax bill this year. "But I don't see the heart or will to get a tax reduction bill through this year. We have a tremendous job ahead just passing the appropriations bills, revenue sharing and the budget resolution," Ullman said. Only three of 13 appropriations bills for the current fiscal year have been passed by Congress. a

Passing a tax-cut bill as well "would have to be with the concurrence of the president and the House leadership," Ullman said.

Although Ullman didn't say so, House sources speculated that Ullman and other leaders such as Rep. John Brademas (D-Ind.), also defeated last Tuesday, would be in no mood to give Reagan a tax bill as a welcome mat.

Complicating the task of Dole and other tax-cut proponents are the differences between the Senate Finance Committee bill and the tax-cut proposal Reagan supported during the campaign.

Reagan economic adviser Alan Greenspan said that the two proposals are very close "in spirit," minimizing the differences between the 10 percent-a-year across-the-board tax cut backed by Reagan, and the mixture of individual and corporate tax reductions approved by the Finance Committee.

But Caspar W. Weinberger, a close Reagan associate and member of his transition team, predicted yesterday that Reagan would not compromise on his call for the 10-percent tax-cut measure.

"That's what he wants," Weinberger said in an interview. "Maybe a lot of people don't understand him. It's a clear, straightforward tax proposal, and I think he'll push for it very hard."

Rep. Robert Michel (R-Ill.), a candidate for the miniority leader's post in the House, said yesterday that a tax bill shouldn't be acted on this year. "I think we should wait until January for the additional votes and do it right, rather than go at it haphazardly in the lame-duck session."