A recent paper by Mr. Hertel-Fernandez and two colleagues may foretell what Democrats can expect if Mr. Uihlein and his fellow philanthropists succeed. It found that the Democratic share of the presidential vote dropped by an average of 3.5 percentage points after the passage of so-called right-to-work laws allowing employees to avoid paying union fees. That is larger than Democrats’ margin of defeat in several states that could have reversed their last three presidential losses.

The weakening of unions also has large downstream effects both on who runs for office and on state legislative policy. Fewer working class candidates serve in state legislatures and Congress, and state policy moves in a more conservative direction following the passage of right-to-work laws.