Republicans have opened up an advantage in a national redistricting battle among states after court rulings that weakened federal Voting Rights Act protections for minorities and invalidated a key Democratic redistricting effort.A recent U.S. Supreme Court ruling that struck down a Black-majority congressional district in Louisiana as an illegal racial gerrymander has provided grounds for Republicans in several Southern states to try to eliminate House districts with large minority populations that have elected Democrats.Meanwhile, a Virginia Supreme Court ruling invalidated a voter-approved congressional map that Democrats had been counting on to deliver as many as four additional U.S. House seats. The court said Democratic lawmakers had violated the state constitution when placing the proposal on the ballot. Legislative voting districts typically are redrawn based on census data after the start of each decade. But an unusual spate of mid-decade redistricting broke out after President Donald Trump urged Texas Republicans last year to reshape U.S. House districts to give the party an edge in the midterm elections. Democrats in California countered with their own political gerrymandering. More states followed.