Union leaders plan to hold their own "shadow convention" this summer to promote labor issues they say both Democrats and Republicans are ignoring.
The union gathering in Philadelphia on Aug. 11 was inspired by the anger many labor officials felt after Democrats decided to stage their nominating convention in North Carolina, a right-to-work state that is the least unionized in the country.
Most unions still plan to attend the Charlotte, N.C., convention, but more than a dozen are boycotting it.
The Philadelphia rally will feature thousands of union members and a "union bill of rights" that officials hope becomes a talking point at both the Democratic and Republican Party conventions.
Some Democrats see the event as an unwanted distraction that highlights divisions among traditional political allies.