A judge has ordered that nine polling places in Harris County, Texas — home to Houston and the most populous county in Texas — extend their voting hours after reports that the sites did not open on time Tuesday morning.

The order by a state district judge came after an motion for a temporary restraining order was filed by the Texas Civil Rights Project and Texas Organizing Project. According to the groups’ court filing, an attorney representing the county’s election officials declined to voluntarily extend the voting hours during a phone call with the groups on Tuesday, prompting the organizations to file the lawsuit.

Texas law requires that polling places remain open for a minimum of 12 hours. The nine polling places will stay open until 8 p.m. local time, according the judge’s order.

The race for Texas’ U.S. Senate seat between Sen. Ted Cruz (R) and Rep. Beto O’Rourke (D) is one of the most closely watched in the nation and could decide which party controls the upper chamber.