But conservative groups have other ideas, and are planning to hold a counter rally just steps away at the same time.
Supporters of Wisconin Gov. Scott Walker's efforts have just obtained a permit for their own demonstration at noon, just a short walk away from the the statehouse annex.
"The counter-protest will galvanize taxpayers from across the state," a group called Americans for Prosperity said in a statement.
Participants will include Tea Party activists, the group said. They plan "to take a stand against the demands of the state worker unions," the AFP said.
Meanwhile, the AFL-CIO is bringing in two public workers from Wisconsin who have been protesting Gov. Walker's effort to curtail collective bargaining there.
The union will also have National AFL-CIO President Richard Trumka and National CWA President Larry Cohen to headline the statehouse rally "in unity and support (of) the workers in Wisconsin."
Organizers say union members from across the state are being recruited to come to Trenton Friday.
"We must work collectively as one labor movement and understand that we need to improve the quality of life for all workers and not dismantle it," the AFL-CIO said.