Texas state House Democrats plan to leave to break quorum of a special session in which Republicans aim to pass a new congressional map that could net the GOP five seats.

Texas House Democrats left Austin for Chicago on Sunday in an attempt to prevent the state House from voting Monday on a redistricting bill. “As of today, this special session is over,” Democrats said in a statement.

In a dramatic escalation of opposition to redistricting efforts led by Republicans in Texas, the Texas Senate Democratic Caucus have expressed strong support for their House counterparts, who have denied quorum in protest of a proposed congressional map they call “rigged” and disenfranchising.