They are also much better funded than people might think. The Center for Media and Democracy (CMD), which monitors the constitutional convention movement, estimates that it pulled in $25m (£22m) in 2020, the last year for which figures are known.
The funds were split between Cosa and other influential groups on the right. They include the American Legislative Exchange Council (Alec), a network of state politicians and corporate lobbyists which has taken up the cry for a constitutional amendment to force balanced budget restrictions on Washington.
Much of the income is dark money, with the origins hidden. CMD has managed to identify some key donors – among them the Mercer Family Foundation set up by reclusive hedge fund manager Robert Mercer, and a couple of groups run by Leonard Leo, the mastermind behind the rightwing land grab in the federal courts.