A federal judge has stopped the 2020 census from finishing at the end of September and ordered the once-a-decade head count of every U.S. resident to continue for another month through the end of October, saying a shortened schedule likely would produce inaccurate results.

U.S. District Judge Lucy Koh in California made her ruling late Thursday, two days after hearing arguments from attorneys for the Census Bureau, and attorneys for civil rights groups and local governments that had sued the Census Bureau in an effort to halt the 2020 census from stopping at the end of the month. Attorneys for the civil rights groups and local governments said the shortened schedule would undercount residents in minority and hard-to-count communities.

Koh said inaccuracies produced from a shortened schedule would affect the distribution of federal funding and political representation. The census is used to determine how $1.5 trillion in federal spending is distributed each year and how many congressional seats each state gets.

Government attorneys had argued that the census must finish by the end of September to meet a Dec. 31 deadline for turning over numbers used for deciding how many congressional seats each state gets.

Koh’s preliminary injunction suspends that end-of-the-year deadline, too. The San Jose, California-based judge had previously issued a temporary restraining order prohibiting the Census Bureau from winding down field operations until she made a ruling in the lawsuit.

Attorneys for the Census Bureau and the Department of Commerce, which oversees the agency, had said during the hearing they would likely appeal.