WASHINGTON » Labor unions at the heart of a burning national disagreement over the cost of public employees want to frame the debate as a civil rights issue, an effort that might draw more sympathy to public workers being blamed for busting state budgets with generous pensions.

As part of that strategy, unions are planning rallies across the country on April 4 — the anniversary of Martin Luther King Jr.’s assassination. Union officials want the observances in dozens of cities to remind Americans that King was supporting striking sanitation workers in Memphis, Tenn., the night he was shot.

By portraying collective bargaining as a human rights issue, union officials hope the rallies can help fuel a backlash against Republicans in Wisconsin and other states trying to curb collective bargaining rights for public employees.

"This is a fight for workers, this is a fight for the middle class, this is a fight to try to stave off the shift in power and wealth that is starting to become gross," said Harold Schaitberger, president of the International Association of Fire Fighters.

The planned rallies on the 43rd anniversary of King’s death are part of a coordinated strategy by labor leaders to ride the momentum of pro-union demonstrations and national polls showing most Americans support collective bargaining rights as Wisconsin Gov. Scott Walker and other Republican leaders in states fight to reduce or strip those benefits.

Walker has argued that collective bargaining is a budget issue. He signed into law yesterday a bill the strips nearly all collective bargaining benefits from most public workers, arguing the move will give local governments flexibility in making budget cuts needed to close the state’s $3.6 billion deficit.

"That’s something people forget about Dr. King," said Liz Shuler, secretary-treasurer of the AFL-CIO, the nation’s largest labor federation. "We all know about his work in the civil rights movement, but he was also a workers’ rights advocate."

It’s also another signal that labor leaders are trying to broaden the coalition of groups speaking out against efforts to limit collective bargaining rights for public employee unions. Unions are coordinating the rallies with the NAACP, the Leadership Conference on Civil and Human Rights and other civil rights, religious and progressive groups.

"King lost his life struggling to help sanitation workers — public-sector employees — achieve their goals for a dignified existence as workers," said Wade Henderson, president of the Leadership Conference. "We think that’s an extraordinary backdrop in which to frame the debate over what’s taking place in the country today."