The California Republican Party filed a federal lawsuit on Wednesday to block the state's newly approved congressional district boundaries, just a day after voters passed the new map.

The ballot measure, which created the new district lines, was designed with the goal of securing five additional congressional seats for Democrats out of California’s 52 districts. It passed easily in the recent vote.

State Assemblyman David Tangipa, the lead plaintiff in the lawsuit, held a press conference to announce the legal challenge. 

He was joined by Corrin Rankin, chairwoman of the California Republican Party, and attorneys with the Dhillon Law Group, a California-based firm founded by Harmeet Dhillon, who now works for the U.S. Department of Justice.

The lawsuit, supported by 18 co-plaintiffs, argues that the new districts violate the 14th and 15th Amendments, alleging unconstitutional gerrymandering under Proposition 50.