Texas Attorney General Ken Paxton on Wednesday sued the U.S. Department of Labor over a proposal to extend family leave benefits to married gay couples.

The proposal, scheduled to take effect next Friday, alters the federal definition of “spouse” in the Family Medical Leave Act to include the legal husband or wife of a gay worker. Under the law, employers must allow unpaid time off for employees facing certain family emergencies.

Texas, as an employer, would be directed to grant such benefits to married gay couples.

In 2005, Texas voters approved an amendment to the state constitution which defines marriage solely as a heterosexual union and does not recognize the out-of-state marriages of gay couples.

“This lawsuit is about defending the sovereignty of our state, and we will continue to protect Texas from the unlawful overreach of the federal government,” Paxton said.

“Texans have clearly defined the institution of marriage in our state, and attempts by the Obama administration to disregard the will of our citizens through the use of new federal rules is unconstitutional and an affront to the foundations of federalism,” he added.

Last year, a federal judge struck down Texas' restrictive marriage ban. The case is currently before an appeals court.

Neel Lane, an attorney who is representing plaintiffs in the case, called the lawsuit “politically motivated” and “doomed to fail.”

“In this case, Paxton is persecuting law-abiding citizens who simply happen to be gay or lesbian,” Lane told The Dallas Morning News.