Peter F. O'Malley, the former political kingpin of Prince George's County, dispatched one of his law partners here this week to kill legislation that would have taken a tax break from the Washington Capitals hockey team. O'Malley is a former president of the National Hockey League franchise, which is owned by O'Malley's close friend Abe Pollin.

The lawyer, Glenn Harrell, carried out his assignment. He arrived here Thursday and went straight to the second floor of the Lowe House Office Building, where he paid calls on members of the county's delegation.

By 9:30 a.m. today, the legislation was dead by a 12-9 vote, and the Caps' tax break was intact.

To accomplish that, Harrell had to persuade the all-Democratic Prince George's delegation to take the almost unprecedented action of refusing a routine courtesy to one of its members. Del. Frank Pesci had sought a waiver of a rule that prohibits introduction of local bills once the 90-day session has begun.

The legislation would have revoked the action by the Prince George's County Council last summer that reduced from 10 percent to 0.5 percent the amusement tax the hockey team pays on each ticket sold to its games at the Capital Centre in Landover. The council acted after Pollin, who also owns the arena where the Caps and his basketball Bullets play, demanded the concession, saying that without it he would move the hockey franchise, which was struggling financially as well as against opponents.

After today's vote, Pesci retired to his office, which includes a poster that says "End political bossism," and attacked his colleagues and O'Malley.

"They voted against the motion because they want to stifle debate," Pesci said. "That's what O'Malley wants. He still controls things up here, that's fairly obvious from this vote. A courtesy is a courtesy. Representatives of the people should give the people the chance to be heard on an issue."

Pesci's suggestion that O'Malley runs the delegation angered Charles J. Ryan, the delegation's chairman. "To suggest that Peter Francis Aloysius O'Malley runs this delegation is ridiculous," Ryan said. "I made no comment on the bill. I did no lobbying. All this vote shows is that this delegation supports home rule."

Pesci said that Harrell came to his office about 8:45 a.m., shortly before the vote, and asked him to withdraw the motion.

"Glenn Harrell certainly earned his money. He came in here with a straight face and told me this would hurt the team," Pesci said.

The delegate said he asked Harrell the outcome of last night's Caps game at the Centre against the Minnesota North Stars. When Harrell reported that the Caps won, 3-1, Pesci said he told Harrell he was "glad they managed to win in spite of spending hours wondering how much money Abe Pollin was going to have to pay the county in taxes."

Harrell's pitch to the legislators was the same one he and O'Malley made to the County Council earlier this year when Council member Sue V. Mills introduced a bill that would have repealed the exemption. Mills, an avowed O'Malley enemy, was the only council member who opposed the exemption last year when it was approved, 10-1.

"I told them, why consider this now when it won't go into affect until next year anyway," Harrell said. "If they do, you will have this controversy swirling around the players just when they are in the middle of a very successful season."

(The Caps are enjoying their best year ever. They have a 26-16-12 record, are in third place in the Patrick Division and are likely to make the playoffs for the first time in their nine-year history.)

The waiver sought by Pesci would have allowed the bill to be introduced and discussed at a public hearing. Just before the introduction of Pesci's bill, Del. Frank Santangelo sought a waiver to introduce a bill on behalf of County Executive Parris Glendening that would increase the county's piggyback tax.

"I'm against that bill," Pesci said. "But it's common courtesy to let someone at least have a public hearing on a bill. So I voted to suspend the rules. Then I leaned over to Santangelo and said, 'You should do the same for my bill.' He just shrugged."

Santangelo went along with the reasoning of Del. Gerard F. Devlin, one of O'Malley's most loyal friends in the delegation.

"This county voted for home rule overwhelmingly in 1970," Devlin said. "The county council took action on this exemption last year and will probably take action again when the season is over. If we allow this bill to be introduced, we're setting a bad precedent. It would be outrageous for us to second-guess the council this way."

Del. William R. McCaffery, who works part-time as a sportswriter and attends many games at Capital Centre, followed with a similar speech.

Del. Lorraine M. Sheehan, in her final meeting as a delegate before being sworn in this afternoon as Secretary of State, sided with Pesci. "We know from what we hear doorknocking during the campaign that this is an issue that upset a lot of people," Sheehan said.

Today's vote left two delegates not speaking to each other, and brought accusations of demagoguery from both sides. And it brought back memories of the days when O'Malley was king of Prince George's politics.

O'Malley usually stays above the fray when his old enemies take shots at him in public. But today, informed of Pesci's comments, O'Malley said indignantly: "I think Mrs. Mills would be wise to get a more effective water carrier than Frank Pesci in the future."

A few moments later, when Devlin walked into the office of Del. Timothy F. Maloney, Pesci, who was there, stalked out.

"Talk to him," Maloney said.

"I'd rather not," Devlin said. "Maybe now, he'll stop demagoguing on things. It's as outrageous for us to consider this bill as it would be for us to consider a bill ordering American troops out of Lebanon."

Pesci had a final comment: "All 12 of them should be ashamed of themselves."