Leaders of the Senate Commerce Committee expect the panel to approve a controversial telecommunications bill today in an environment that may lead to a White House order shutting down the Justice Department's landmark antitrust case against the Bell System.

Despite the relative ease with which supporters expect the Commerce Committee to pass the bill, committee chairman Robert Packwood (R-Ore.) has told administration officials, including President Reagan, that any telephone bill is dommed in the House as long as the antitrust suit against American Telephone & Telegraph Co. continues. Congress, Packwood complained, is "impotent" faced with the Justice Department case.

That view is based primarily on House Judiciary Committee action blocking similar legislation last year. But Rep. Timothy Wirth (D-Colo.), chairman of the House telecommunications subcommittee, who is moving more slowly towards legislation, says both the Senate bill and the rationale for dropping the suit are flawed. Wirth expects to consider legislation in the fall.

"The legislation ought to take into account the users," Wirth said yesterday."You deregulate where you have competition. The purpose should be to nurture and encourage competition. They'll kill all the competition. Why is this train running down the track so fast?"

Wirth, who has written the White House urging that the antitrust suit not be dropped, said he and Rep. Peter Rodino (D-N.J.), chairman of the Judiciary Committee, met yesterday and have begun unusual staff talks designed to avert last year's disagreement. To drop the suit, Wirth said, would "say the whole world is caving in to AT&T, forgetting about the concerns of users and competitors and we'll have one mammoth company running our communications system."

Meanwhile, Packwood, the chief sponsor of the bill and the committee's chairman, says he has the votes to easily pass the bill, particularly since both the newspaper and cable television industries appear certain to back it if language Packwood has endorsed is approved by the full committee.

He has succeeded in winning support for the bill from a former, key opponent, the American Newspaper Publishers Association.The bill's supporters may also be able to claim the support of AT&T, most independent telephone companies, cable television representatives, and International Business Machines Corp.

The case against the AT&T suit has been forcefully made by the Commerce and Defense Departments, with Commerce arguing that the ongoing trial is certain to lead to lenghy appeals.

Further, the Commerce officials argue that the Justice Department goals of AT&T divestiture -- breaking off separate companies for AT&T long distance and manufacturing operations -- is inappropriate in an era when the industry is in some ways truly competitive and fighting foreign competition.

From Defense comes the argument that the government's ability to coordinate national emergency planning needs would be hurt by splitting up AT&T.

A member of the White House Council of Economic Advisers, who has expressed concern about the legislation, says the suit should not be dropped unless there is an acceptable legislation solution to the problems of the industry.