Facing an alarming shortage of poll workers due to the pandemic, unions have begun recruiting their members to help keep precincts open.
Law enforcement unions make up a small slice of the AFL-CIO, but progressive members are increasingly uncomfortable associating with them.
Some states are already laying out plans to let nonessential businesses reopen their doors to workers and customers.
The AFL-CIO backed about 1,500 union members in the 2018 elections, and two-thirds of them won.
"Our members are still waiting for the supposed greatness of this economy to reach their kitchen tables," Richard Trumka told Chris Wallace on Fox News.
In a closed meeting, AFL-CIO President Richard Trumka told the campaigns that Democrats shouldn't expect union support if they don't change their ways.
A loud voice for job security, the union group is taking heat from its own workers who say theirs is being undermined.
Bernie Sanders' comments came as fissure cracks open between the president and the nation's largest union.
One person wondered if the president's tweet was "some kind of lame attempt to be able to say you 'celebrated' Labor Day."
Come November, his members will "probably" back Democratic candidates.