The largest teachers’ union in Kansas has filed a lawsuit against a new state law that ended guaranteed tenure for public school teachers.

The Kansas National Education Association argued Monday that the law violated the state constitution for the anti-tenure policy to be added to a larger education funding measure.

The lawsuit filed in Shawnee County District Court alleges the Republican-dominated Legislature violated a provision of the state constitution requiring most bills to contain only one subject.

However, the 23,000-member union is asking a judge block only the anti-tenure provision.

The measure approved by legislators in April boosted state aid to poor school districts by $129 million for the new school year. Conservative GOP legislators insisted on tying the new funding to other policy provisions, including the one on tenure.