Organized labor officials fighting efforts to force greater disclosure of union political activities have unearthed a decade-old memo from former Speaker Newt Gingrich (R-Ga.) that appears to support contentions that some Republicans have sought changes to the reporting rules in order to undercut labor’s impact on the campaign trail.

The memo, which was sent by Gingrich to then-Labor Secretary Lynn Martin and Clayton Yeutter, who served at the time as the first President George Bush’s domestic policy chief, recommended stiffer disclosure requirements for unions, noting, “It will weaken our opponents and encourage our allies.”

The document, which was marked as received at the Labor Department on Feb. 21, 1992, could hardly have fallen into labor’s hands at a more propitious moment.

The unions are facing an urgent battle to derail Bush administration rulemaking on the disclosure issue — one that labor insists is politically motivated. The 1992 find is almost certain to add new rhetorical weight to the allegation on Capitol Hill, where labor is now waging the bulk of its fight.

“Back then, just as now, [the GOP has] denied that this is politically motivated. Well, this looks like a smoking gun to me,” said Jonathan Hiatt, the AFL-CIO’s general counsel. “This is as close to an admission that you could possibly find.”

The memo was obtained by the AFL-CIO this week through the Freedom of Information Act.

Mike Mathis of the International Brotherhood of Teamsters said the document would provide new ammunition to labor activists battling the Labor Department in Congress. The most likely forum would be the Appropriations committees, where the unions have already succeeded once — albeit briefly — in getting language that would have blocked action on the matter. The fight on union disclosure is rooted in a 15-year-old Supreme Court decision that addressed how union political activities are financed. In Communications Workers of America v. Beck, the justices ruled that non-union workers cannot be forced to pay for union political activities with which they disagree — even if they could still be compelled to pitch in for other organized labor activities, such as collective bargaining.

In the aftermath of the 1988 decision, GOP conservatives immediately began efforts to convert its spirit into law. Among other things, they sought rules that would require employers to post workplace notices informing workers of their rights under the Beck decision, and they sought changes to require fuller disclosure of expenditures in the form — called an LM-2 — that unions use to account for their spending in political campaigns.

The latter of those efforts culminated in the current proposed rulemaking at the Labor Department. The comment period on the proposal closed March 29.

Unions have insisted from the get-go that compliance with the new rules would be too costly and burdensome, though perhaps their more trenchant concern can be detected in suspicions that GOP strategists want to get hold of labor’s political playbook.

Labor Department spokeswoman Kathleen Harrington said the department is trying to provide transparency in order for workers to “self-govern,” and she rejected the suggestion that compliance would be too costly or that the effort is politically motivated.

“I think that is a clever but very unfortunate mischaracterization,” Harrington said of the allegations. “While it might be a good bumper sticker to lead an opposition campaign to this effort, it fails to effectively understand and evaluate the objectives of this proposal.”

But the memo from Gingrich, who was once the GOP’s foremost tactician, will tempt suspicions. The former Speaker, who at the time was the Minority Whip, sent copies of the document to White House Chief of Staff Samuel Skinner; his deputy, Henson Moore; Bush campaign chairman Bob Teeter; Fred Malek, the campaign manager; Mary Matalin, the deputy campaign manager; and Commerce Secretary Robert Mosbacher.

Gingrich asked the Labor Department to take action on the matter by the end of March, calling it “long overdue.”

Gingrich spokesman Rick Tyler said on Friday that the former Speaker would not be interested in discussing the LM-2 matter. “It doesn’t fit anything he’s doing right now,” Tyler said.

In mid-April 1992, then-President Bush took action, signing an executive order that required federal contractors to post notices at job sites informing non-union workers of their right to withhold their share of dues from union political activities. Separately, the Labor Department announced a new rule that would require unions to designate how much they spend in each of three areas: political activities, lobbying and contract negotiations.

President Bill Clinton subsequently declined to enforce the new rules when he took office the following January. But the issue returned to the table when the second President Bush was elected in 2000.