A federal judge is blocking an Obama administration rule that would extend mandatory overtime pay to more than 4 million salaried workers on December 1.

On Tuesday, U.S. District Judge Amos Mazzant, in Texas, agreed with 21 states and a coalition of business groups, including the U.S. Chamber of Commerce, that the rule is unlawful and granted their motion for a nationwide injunction.

The regulation would more than double the salary threshold at which employers must pay overtime to their workers.

Critics say the regulation would cut into employer profit margins.