A federal judge in Texas has temporarily blocked implementation of a plan to extend family leave benefits to married gay couples.

U.S. District Judge Reed O'Connor granted the preliminary junction sought by Texas Attorney General Ken Paxton (pictured) that stays expansion of the federal definition of “spouse” in the Family Medical Leave Act to include the legal husband or wife of a gay worker.

The change was set to take effect Friday.

Under the law, employers must allow unpaid time off for employees facing certain family emergencies.

Paxton argued that the new regulation would force state agencies to violate Texas' 2005 voter-approved constitutional amendment defining marriage as a heterosexual union.

“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 in filing the lawsuit.

“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.

Arkansas, Louisiana and Nebraska joined the lawsuit.

“No legally married same-sex couple should be denied family leave simply because they happen to live in a state that fails to respect their marriage,” HRC Legal Director Sarah Warbelow said in a statement. “Because of Judge O’Connor’s decision, countless legally married same-sex couples in Texas are now unable to access their federal FMLA benefits. With a pending Supreme Court decision on nationwide marriage equality this summer, we are confident that justice will ultimately prevail.”

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