California Democrats are rushing to schedule an election to remake U.S. House districts to counter plans to boost Republican seats in Texas.

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.

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.