Ten additional states are suing the Obama administration to stop a directive that requires schools to allow transgender students to use bathrooms aligned with their gender identity under the threat of losing federal funding, bringing the total number of states challenging the guidance to 21.

Nebraska Attorney General Doug Peterson announced the lawsuit, filed in federal court in Nebraska, on Friday afternoon. The state is joined by nine others: Arkansas, Kansas, Michigan, Montana, North Dakota, Ohio, South Carolina, South Dakota and Wyoming.

The Obama administration, via the departments of Education and Justice, issued guidance to schools in May directing them to allow transgender students to use bathrooms that align with their gender identity, a move that plunged the administration further into the debate over how schools and the public should accommodate transgender people.

Lawmakers, school administrators, parents and the courts have been arguing over the issue. Lesbian, gay, bisexual and transgender advocates say barring transgender people from the facilities that align with their gender identities is a violation of their civil rights that threatens their well-being. But those who support such rules say they are necessary to safeguard privacy and traditional values.

Peterson argued that the administration bypassed the necessary procedures to create new federal regulations, in this case regulations that apply to every public school in the nation. Peterson also is asking for an injunction to stop the guidance while his lawsuit proceeds.

“The recent action by these two federal agencies to require showers, locker rooms, and bathrooms be open to both sexes based solely on the student’s choice, circumvents this established law by ignoring the appropriate legislative process necessary to change such a law,” Peterson said. “When a federal agency takes such unilateral action in an attempt to change the meaning of established law, it leaves state and local authorities with no other option than to pursue legal clarity in federal court in order to enforce the rule of law.”

This is the second lawsuit brought by a group of states over the Obama administration’s move to expand the rights of transgender students. Eleven states, along with the Arizona Department of Education, filed a lawsuit in federal court in Texas two weeks after the guidance was issued, arguing that the administration had overstepped its authority.

This week, Texas Attorney General Ken Paxton asked the court to allow localities to ignore the guidance while the case proceeds, hoping to stop it in its tracks before school starts in the fall.

In an appearance in Washington on Thursday, Paxton leveled sharp criticism against the Obama administration’s directive on transgender students, calling it a “gun to the head” that threatens the independence of school districts to handle the issue as they see fit.