Democratic-aligned voting rights organizations are bracing for what they describe as a potential crisis if the U.S. Supreme Court moves to weaken a central provision of the Voting Rights Act, one of the nation’s cornerstone civil rights laws.

The concern centers on Louisiana v. Callais, a case the justices heard on October 15. The outcome could determine the future of Section 2 of the Voting Rights Act, which prohibits redistricting plans that dilute the voting power of racial minorities.

Two prominent voting rights groups have warned that striking down or narrowing Section 2 would allow Republican-controlled legislatures to redraw as many as 19 congressional districts in their favor, PoliticoThat projection — outlined in a new report from Fair Fight Action and the Black Voters Matter Fund and shared exclusively with POLITICO — suggests that striking down Section 2 of the Voting Rights Act could all but ensure continued Republican control of the House of Representatives.While a ruling before next year’s midterm elections remains uncertain, the organizations behind the report said it is still possible. In total, the groups identified 27 congressional seats nationwide that could be redrawn to favor Republicans if current legal and political conditions hold — with 19 of those shifts directly tied to the potential elimination of Section 2 protections.