The president of Maryland's largest union group threatened today to organize a customer boycott against 17 of the state's largest corporations for underwriting a campaign to defeat politicians they consider labor's allies.

The comments today by Edward R. Lamon, president of the 400,000-member Maryland State & D.C. AFL-CIO, followed the release last week of a four-page newsletter by a business group that rated the performance of every state legislator except the president of the Senate and the speaker of the House of Delegates.

Lamon said he would ask his executive board Friday to approve the withdrawal of millions of dollars in union pension funds from five giant Maryland banks that were among those corporations that helped fund the "report card" of legislators' votes on key business issues.

"We call it a hit list," Lamon told reporters at a news conference here today. "Placing labels on public officials in this state cannot remain unnoticed."

Lamon's threat to organize a boycott against Crown Central Petroleum Corp., Perdue Farms Inc., and other corporate sponsors of the newsletter was the latest salvo in a war of words over the political strategies of a group called Maryland Business for Responsive Government. The group was founded in 1983 with funds from several large Maryland corporations and is making its first real foray into state politics this year when nearly every public official in the state is up for election.

Last week, the group issued the newsletter in which legislators received a percentage rating on how they voted on select bills that MBRG deemed important to Maryland's overall business climate. The votes occurred in the past four regular sessions of the General Assembly.

Lamon announced that his union also had compiled legislator ratings for the past 30 years, but union officials never disclosed them. To have done so, he said, "would be unfair to those who vote with us and those who have reason to vote against some of our bills."

However, a few minutes later, Lamon disclosed the poor ratings the union recently bestowed on Dels. Martha S. Klima and Ellen R. Sauerbrey, two Baltimore County Republicans who received perfect ratings from MBRG.

Robert O.C. Worcester, MBRG's executive director, attacked Lamon's remarks as disingenuous.

"They have been provoked into saying publicly what they have been doing privately for decades: silently bullying people and intimidating people in the halls of Annapolis," Worcester said after reviewing a copy of Lamon's prepared statement.

Worcester also sharply criticized Lamon for threatening to boycott the corporations, calling the union president "totally archaic, totally punitive and totally negative."

Worcester went on to defend MBRG's scorecard as simply part of the public record. He described the rating as a guide for those corporate leaders who will contribute to political campaigns in this watershed election year.

Lamon, meanwhile, said the union will work this fall "to protect our friends" in the legislature. He added that he may destroy five Crown Central credit cards the union recently obtained for its executives.

"This may be war, but we didn't start it," said Lamon.