After organizing rallies around the country during Wisconsin's legislative fight over collective bargaining, the labor movement will try to make April 4 a massive day of nationwide mobilization.

The AFL-CIO, the Service Employees International Union (SEIU), the National Education Association (NEA), and other unions are organizing rallies across the country on the anniversary of Dr. Martin Luther King, Jr.'s assassination.

When King was shot, 43 years ago next month, he was in Memphis to lend his support to a strike by sanitation workers.

Labor is encouraging the attendance of planned rallies, and the planning of new rallies, though a website that supplies locations and resources. It's reminiscent of the FreedomWorks site in early 2009, as that group sought to assist in coordinating tea party protests.

After Wisconsin Gov. Scott Walker stirred the labor movement's ire, union organizers will try to keep up the energy and organization. April 4, it appears, will be the first test.