MONTGOMERY, Ala. >> Lawmakers in several southern states are meeting this week to consider plans that could upend their congressional primaries and redraw U.S. House districts ahead of the November elections, as Republicans move quickly to capitalize on a U.S. Supreme Court ruling that weakened a key provision of the Voting Rights Act.

A special legislative session responding to the court ruling began Monday in Alabama and is to start Tuesday in Tennessee. Louisiana lawmakers, who already are in session, also are looking at how to redraw their congressional districts. The Supreme Court on Monday essentially gave them a green light to proceed by approving a request to expedite the court’s formal judgment.

Civil rights activists have countered with rallies, protests and lawsuits challenging the new redistricting efforts. Several hundred protesters gathered outside the Alabama Statehouse on Monday, carrying signs declaring “No new map” and “We fight back! Black Voters Matter.”

Last week’s Supreme Court decision striking down a majority-Black congressional district in Louisiana has unleashed “a wave of nefarious actions” across states that threatens to disenfranchise Black voters, Alanah Odoms, executive director of the American Civil Liberties Union of Louisiana, said Monday.

Trump on Sunday encouraged more states to join in redistricting, saying in a social media post that Republicans could gain 20 House seats. But South Carolina Gov. Henry McMaster’s office on Monday said the Republican would not call a special session to redraw the state’s only Democratic-occupied House seat.

The high court’s ruling said Louisiana relied too heavily on race when creating a second Black majority House district as it attempted to comply with the Voting Rights Act.

Legislative voting districts typically are redrawn only once a decade, after a census, to account for population changes. But Trump urged Texas Republicans last year to redraw U.S. House districts to give the party an advantage. Democrats in California responded by doing the same, and then other states joined in.

On Monday, Florida became the eighth state to enact new House districts ahead of midterm elections, as Republican Gov. Ron DeSantis announced he had signed a redrawn map passed by lawmakers last week that could help Republicans win as many as four additional House seats. The new map was immediately challenged in court as a partisan gerrymander that violates a state constitutional provision against drawing districts that favor one political party over another.

All told, Republicans think they could gain as many as 13 seats from new congressional districts in five states, while Democrats think they could pick up as many as 10 seats from new districts adopted in three states. The newly proposed redistricting in southern states could add to the Republicans’ tally.

After last week’s Supreme Court decision, Louisiana moved quickly to delay its May 16 congressional primary to allow time for lawmakers to approve new U.S. House districts. But Republicans have yet to unveil their planned revisions to district lines.

Democrats and civil rights groups have filed several lawsuits challenging the election suspension, including another suit filed Monday in federal court.