Plans by the House Ways and Means Committee to resume work this morning on President Carter's tax cut package ran into a new and potentially serious snag yesterday, threatening to place the entire bill in jeopardy again.

A mid-morning meeting of the panel to take up the compromise Jones substitute for the Carter tax package was canceled abruptly yesterday after liberals balked at a provision that would slash taxes on capital gains.

Sources said several liberals indicated they plan to support a revived version of the so-called Vanik-Pickle amendment, which essentially would abandon all tax cut legislation and merely continue the tax rate now in effect.

Rep. Al Ullman (D-Ore.), the panel's chairman, was polling Democrats last night to see which measure would be most likely to draw a majority - the Jones substitute, or the Vanik-Pickle provision.

Although Ullman was not available for comment, panel sources indicated the committee may be split almost evenly between the two rival measures, if the Vanik-Pickle measure carried, it would be a major blow to the Carter bill.

The revolt by the panel's liberals apparently came as a surprise to the committee's leaders, who had been confident they had worked out a compromise under which a majority of members would support the Jones proposal.

The tax bill has been on the shelf for six weeks in the face of an earlier threat by the liberals to back the Vanik-Pickle provision if conservatives got their way. Yesterday's breakup showed the rift still has not healed.

The provision to which the liberals objected yesterday was a portion of the Jones proposal that would cut taxes on capital gains to 35 per cent, from 49 per cent now. Capital gains are the profits from the sale of stocks or other assets.

Jones' provision had been intended as a compromise from a proposal by Rep. William A. Steiger (R-Wis.) that would have rolled capital gains taxes back to 25 per cent. It was the rise of the Steiger bill that angered liberals earlier.

Ways and Means leaders thought on Wednesday that the earlier opposition had been dampened, and scheduled a committee meeting for this morning to consider the Jones proposal. However, they apparently misjudged the situation.

Committee sources indicated yesterday if the Vanik-Pickle provision were adopted, it would be sent to the House floor under a parliamentary restriction prohibiting any amendments.

As a result, unless the measure were rejected by the House and sent back to committee, the bill would leave the writing of this year's tax cut entirely to the Senate - if, indeed, the lawmakers vote a tax cut, as expected.

Republicans on the panel are expected to support the Jones substitute, primarily because of the tax reduction it would provide for capital gains. The Jones measure also would revamp Carter's general income tax-cut proposals.

The administration is vigorously opposed to any cutback in capital gains taxes. Secretary of the Treasury W. Michael Blumenthal has called the provision a "fatcat amendment" that would primarily benefit the rich.