Democratic lawmakers said they left the state of Texas in an effort to temporarily block Republicans from redrawing its congressional maps — a redistricting initiative pushed by President Donald Trump.

The GOP-dominated Texas House is set to vote Monday on a new congressional district map that would flip five U.S. representative seats from Democrat to Republican – solidifying the party’s majority in Washington in time for next year’s midterm elections.

There are 150 members of the Texas House, but 100 — a quorum — are needed to conduct business. The House Democratic Caucus announced Sunday afternoon that the majority of Democratic members would break quorum and leave the state ahead of floor debate scheduled for Monday on a proposed congressional map.