Sen. Ernest Hollings (D-S.C.) held up Senate consideration of sweeping telecommunications legislation yesterday, charging that enactment of the bill would "extinguish" competition in the telephone industry.

Hollings spoke without interuption on the Senate floor for more than an hour and a half. "This is a bad measure, and we've got to clean it up," Hollings said.

Hollings called AT&T a "two- headed monster," saying the company has one head "very benevolent, and one very vicious." The legislation, sponsored by Senate Commerce Committee Chairman Bob Packwood (R-Ore.) and the Republican leadership of that committee, would turn AT&T into an "unregulated monopoly," he said.

Hollings' tactic, adopted before the Senate could vote on whether even to begin formal consideration of the bill, worked, delaying further consideration until Monday morning when Hollings will again have the floor.

Hollings said he will offer amendments tightening the divisions between AT&T and any separate subsidiary.

The separate-subisidary concept is the heart of the bill, as it would permit AT&T to enter competitive businesses such as data-processing.

Hollings charged in a later interview that Packwood has failed to discuss the bill and amendments worked out with the Judiciary Committee with other Commerce Commitee members.

"Packwood operates as if there's a conspiracy. . . . He doesn't care about anything, he just runs roughshod," Hollings said. "We've been totally shut out."

Packwood later denied that he or his staff had left the Democrats out of the process, and he defended the bill. "All of the contracts" between AT&T and its affiliate "will be filed at the FCC," he said. "Every single one of their competitors will monitor those contracts, and you're going to have better monitoring under this system than you've ever had at the FCC."

"Where we're afraid to run the risk, we're going to continue the old FCC regulation," he added. "We're not leaping whole hog into a nonregulated telephone system."

Although passage of the bill still appears likely, there was a mixed bag of news in other quarters yesterday. Among other developments:

* A compromise on controversial provisions of the bill limiting municipal regulation of cable television failed to win new support for those sections of the bill. The amendment, sponsored by Packwood and Sen. Howard Cannon (D-Nev.), would maintain municipal regulation of basic cable television rates, but would deny local governments authority to regulate alarm and data services over cable. A spokesman for the U.S. Conference of Mayors said opponents will continue to fight any cable provisions in the bill.

* Sen. Arlen Specter (R-Pa.), a member of the Judiciary Committee, became the first Republican to suggest that he might oppose the bill. Specter said he is "leaning" against support of the bill "because of the absence of competition" in the industry.

* General Telephone & Electronics, a critic of many provisions of the bill, announced "with reservations" that it will support the bill if amendments adopted by the Judiciary and Commerce staffs were added to the measure on the floor.

* Hollings and Senate sources suggested a group of Democrats are poised to fight to revise portions of the bill giving the Department of Defense new powers to alter telecommunications policy.