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 weighing new political maps that could slash five Republican-held House seats in the liberal-leaning state while bolstering Democratic incumbents in other battleground districts.

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,