Democrats in the Texas House have fled in an attempt to prevent a vote Monday on Trump-backed maps designed to add GOP seats in Congress.

To conduct official business, at least 100 members of the 150-member Texas House must be present. Democrats hold 62 of the seats in the majority-Republican chamber. At least 51 Democratic members are leaving the state, said Josh Rush Nisenson, spokesperson for the House Democratic Caucus.

Texas House Democrats left the state Sunday to prevent a vote on the Republican effort backed by President Donald Trump to rewrite the state’s congressional map.