The lawmakers, all Democrats who urged military service members not to follow illegal orders, said prosecutors had contacted them. But it is unclear what crime they might have committed.
Representative Jason Crow of Colorado, one of the lawmakers being investigated, said President Trump was “using his political cronies in the Department of Justice to continue to threaten and intimidate us.”
It is unclear what possible crime might involve Senator Elissa Slotkin, a Democrat, who has warned in dire terms about the dissolution of American democracy.
Senator Elissa Slotkin of Michigan, a former C.I.A. officer, organized a video with five other Democratic lawmakers in which they urged military service members to resist illegal orders.