Republicans in Texas currently hold 25 of the state’s 38 seats, and the new map ups the total they could win to 30. All of those new 30 seats were won by Trump in November by at least 10 percentage points, leading to conservative optimism they can hold them even in what’s likely to be a tough midterm environment for the party.

Cuellar, a moderate Democrat, is one of two Democrats representing a South Texas district won by Trump last November and is viewed as perhaps the most vulnerable incumbent. Cuellar won reelection by more than five points—but Trump won the former Democratic stronghold by about seven points.