Business groups worried about losing friendly House Republicans in fall elections are borrowing a page from organized labor.

After the 1994 Republican takeover of Congress, labor spent $35 million two years ago to help defeat 18 GOP incumbents in the House, narrowing the Republican majority to an uncomfortably thin 11 seats.Now, business leaders are agitating to get their own ranks to counteract yet another aggressive effort this November, led by the AFL-CIO, the umbrella organization for nearly 100 affiliated unions.

Business groups talk about increasing their political action committee contributions - in 1996, they outspent labor by a 6 to 1 margin, $351 million to $59 million, according to the Center for Responsive Politics - while trying to respond earlier to labor's expected flood of radio and television commercials.

Considered one of the GOP's strongest supporters, business groups admit they were unprepared for labor's feisty challenge two years ago and that they need to target their greater financial resources on specific races, much like labor.

"It has gotten our members' attention as to the need to be involved politically," said Dan Danner of the National Federation of Independent Business, a founding member of a group of business organizations called the Coalition.

"A lot of the issues that the unions beat up on candidates about are issues that we disagree with them pretty strongly."

Labor is readying for fresh battle, too.

Next week, the union federation begins training its first class of some 300 volunteers for work in competitive districts. Their assignment: Knock on doors of union members, distribute literature and get them out to vote on Election Day. The volunteers will come from union locals in the targeted districts.

"A lot of union members stayed home in 1994," said Steve Rosenthal, political director of the AFL-CIO. "That had a lot to do with a lot of the Gingrichites being elected. What we want to do is make sure that doesn't happen again."

Beginning in 1995, labor got aggressive, airing a series of issue-oriented TV commercials in key congressional districts, criticizing selected House Republicans for their positions, including on minimum wage and education.

Unions ran other ads in selected districts in 1996 and again in 1997. This year, they have earmarked $28 million - about $2.15 worth of dues per union member - for a similar effort.

The Coalition strategy is to counteract the labor effort, including by sending a videotape to top corporate executives asking for financial support.