President Carter found some new allies yesterday in his flight to save his tax package from defeat in the House Ways and Means Committee - the panel's 12-member Republican minority.

While Democrats generally have been criticizing the president's program, spokesman for the GOP side of the panel visited Carter at the White House yesterday and urged him not to retreat from his original proposal.

"We told him not to panic, that we were willing to cooperate with him in getting a tax bill to the floor," said Rep. Barber B. Conable (R-N.Y.), the committee's ranking minority member.

Rep. William Frenzel (R-Minn.), who accompanied Conable on the visit, said the two advised Carter that the $25 billion in tax cuts he proposed was "right in the ballpark," despite calls by Democrats to trim the amount.

The expressions of support were almost the first Carter has heard in his talks with Ways and Means members over the past few days. Democrats on the panel have warned him the tax package is in jeopardy.

The committee formally laid aside the tax bill yesterday after a week of defeats for Carter's "tax reform" proposals - ostensibly to allow members time to work on the newly revived energy tax bill, now in conference.

However, panel members conceded the delay was designed in part to give the committee a "cooling-off period" in which Democrats could try to work out a compromise on which provisions should remain in the bill.

Ways and Means Chairman Al Ullman (D-Ore.) said yesterday the idea for a recess had been "cleared with the White House." The panel is expected to resume its mark-up of the tax program early next week.

Yesterday, the committee heard a group of prominent economists reaffirm that a tax cut was needed to offset the impact of inflation and higher Social Security taxes. But the analysts differed on the size and structure of the plan.

Some of the economists suggested reducing the size of the proposed income tax cut to $20 billion, from the $25 billion Carter has proposed. Others urged that part of the cut be devoted to rolling back Social Security taxes or spurring more investment.

THe economists included Martin Feldstein of Harvard University; Rudolph G. Penner of the American Enterprise Institute; Alan Greenspan of Townsend-Greenspan and Co.; F. Gerrard Adams of Wharton School of Finance; and Arthur M. Okun of the Brookings Institution.

The appearance was intended in part to dampen support on the committee for a proposal by Rep. Charles A. Vanik (D-Ohio) that would scrap the entire Carter tax program and vote for the measure if the rest of the committee does not support Carter's proposed "reforms."

Although the Vanik proposal at first was considered unlikely to pass, several liberals have warned they will simply extend the cuts enacted in 1976 and 1977.

The visit by committee Republicans marked the last Carter has planned with panel members before knuckling down to deciding what to do about his beleagured tax plan.

Immediately after the session with the Republicans, top White House policymakers began another round of discussions to consider the administration's next strategy step concerning the tax bill. More talks are expected today.

Administration officials have been cautioning that Carter may decide to continue pushing for enactment of his original tax bill, in hopes that if he loses substantial portions in the Ways and Means panel, he can make it up on the floor.

Frenzel said after his visit to the White House yesterday that Carter did not appear to be "in a mood to slow down, or to make some huge change in the package in either direction."

Both Conable and Frenzel said Carter appeared to be concerned that Republicans on the panel had "voted as a bloc" on most of the key "tax reform" votes last week, and expressed concern that GOP members might be "unfriendly."

However, Conable said, the Republicans assured him their votes were intended to make sure the proposals were not designed to redistribute income through the tax system. He said GOP members might vote for some "reforms" on a second round.

Conable also said Carter "seemed to have the idea we Republicans were in favor of a tax cut about twice as large as he proposed. I don't know where he got that impression," he said, "but we told him his $25 billion was right."

Both Conable and Ullman reiterated their assurances yesterday that "there's no reason to panic" over the panel's disarray, and predicted a tax bill would be sent to the floor.

Ullman said the recess was intended partly to head off what he called "railroad psychology," adding that "we have been attempting to move here at a faster pace than can be assimilated." Conable pledged GOP "cooperation" for a bill.