As an overflow crowd of high-priced lawyers and lobbyists looked on, the House Energy and Commerce Committee moved only inches forward yesterday in considering its controversial bill that would alter dramatically the landmark divestiture agreement AT&T signed with the Reagan administration last January.

With AT&T strongly opposing the measure, a handful of congressmen tried to slow the committee's consideration of the measure, which sources say has the support of the majority of the committee.

Leading the fight against the measure, Rep. Tom Corcoran (R-Ill.) insisted that the committee staff read the entire 130-page bill word for word.

At the same time, Corcoran objected to permitting the committee to adopt in a block a package of what the staff said were noncontroversial amendments, insisting that each of the 150 amendments be discussed one at a time.

"When we're dealing with something as complicated, as complex, and as futuristic as the telecommunications industry, we ought to be very careful not to act in haste," argued Corcoran, who, along with Rep. Don Ritter (R-Pa.), complained when the staff read the bill too quickly or skipped some paragraphs.

Corcoran also offered two lengthy amendments opposed by the committee that, among other things, would have ended the Federal Communications Commission's authority over the broadcasting industry and over the allocation of broadcasting frequencies.

These moves eventually evoked sharp criticism from the bill's supporters. Rep. Marc Marks (R-Pa.) charged that the "strategy being used . . . is a deliberate attempt to delay this bill in hopes it will never get through. The subterfuge that these people don't know what's in this bill is baloney." AT&T "ought to learn that, although they have members working in their behalf, they cannot obstruct the process," Marks angrily added as Corcoran refused to dispense with the reading of the bill for the fourth time.

Nonetheless, committee aides expect opponents of the measure to continue their strategy today when the committee resumes consideration of the legislation--so much so that the staff has just about given up hope that the committee can complete action on the measure before it adjourns for the July 4th recess this week.

The stakes on this legislation are quite high. AT&T has mounted a $2-million lobbying campaign, writing letters to its shareholders and running numerous newspaper advertisements against the bill. At the same time, AT&T's competitors, such as International Telephone & Telegraph Co. and General Telephone & Electronics Corp., are mounting a massive radio advertising campaign in support of the measure.

In some respects, the legislation closely follows the outlines of the antitrust settlement that AT&T signed with the Reagan administration on Jan. 8. As the settlement calls for, the legislation would require AT&T to spin off its 22 local operating companies.

However, the bill goes beyond the settlement by imposing tighter restrictions on AT&T's long-distance network and by giving the divested local companies greater opportunities to enter the more lucrative parts of the telecommunications industry than the settlement allows.