A domino effect is shifting candidates into new seats, pushing incumbents to retire and exposing deep political rifts in state parties.

The national redistricting battle triggered by Donald Trump has cast a long shadow over the race for control of Congress next year — not only fundamentally shifting the House battlefield, but also creating a domino effect that’s shifting new candidates into new seats, ushering longtime members of Congress to the exit and exposing deep political rifts in state parties across the country.

The fight is still playing out across courtrooms, back rooms and Trump’s social media, as Republicans and Democrats tinker with district lines. Developments like this week’s federal court ruling blocking the new Texas maps from going into effect — leaving the ultimate decision to the Supreme Court — also show how much remains to be determined in the redistricting fight.

The battle kicked off when Trump started pushing Texas Republicans to redraw district lines in the hopes of netting the party up to five seats in the state, and later began pressing leaders in other GOP-controlled states.