A powerful, deep-pocketed force in California politics endorsed redrawing the state's congressional maps to counter President Trump's effort to push GOP states, notably Texas, to increase his party's numbers in Congress in next year's midterm election.

As a Texas senator summoned the F.B.I. to round up Democrats, the redistricting war that began in Texas was spreading, with California aiming at five Republican House seats.

California Democrats are pursuing a plan to redraw congressional maps amid the efforts in Texas to redistrict, which could hand the GOP five more House seats. David Becker, the executive director at the Center for Election Innovation and Research,