The legal fight over the controversial citizenship question on the 2020 census is likely to continue at San Francisco federal court.

"I believe the case will proceed," U.S. District Judge Richard Seeborg said Friday during a hearing on whether to dismiss two of the lawsuits against the Census Bureau and the Commerce Department, which oversees the census.

Seeborg did not issue a formal ruling from the bench, but he pushed back on many of the Justice Department attorneys' arguments in support of Commerce Secretary Wilbur Ross' decision to add a question about U.S. citizenship status — a topic the Census Bureau has not included in the census for all U.S. households since 1950.

"They're saying effectively this is a poison pill to the count for the purposes of depressing the count," Seeborg said in summing up the plaintiffs' position.

If Seeborg allows these two lawsuits to move forward, a potential trial could start on Jan. 7.

The Trump administration is fighting a total of six lawsuits from dozens of states, cities and other groups that want the question removed from forms for the 2020 census.

Ross has said he approved the question because the Justice Department needs responses from it to better enforce the Voting Rights Act's provisions against racial discrimination.

California Attorney General Xavier Becerra filed the first lawsuit, on behalf of the state of California, after Ross announced the addition of the citizenship question in March.

The city and county of Los Angeles, plus four other cities in California, later joined that case at the U.S. District Court for the Northern District of California. The city of San Jose, Calif., and the Black Alliance for Just Immigration, a California-based immigrant-rights group led by Black Lives Matter co-founder Opal Tometi, have filed a separate legal challenge.

Last month, a judge in New York ruled that two cases at Manhattan federal court may head to a potential trial beginning as early as late October.

A federal judge in Maryland is expected to rule soon on whether to dismiss another lawsuit over the citizenship question brought by a group of residents from that state and from Arizona.

All of these plaintiffs argue that the citizenship question could reduce federal funding to their local schools, highways and other public institutions and services that rely on dollars distributed on the basis of the population count. They cite Census Bureau research that suggests asking about citizenship status will discourage noncitizens from participating in the constitutionally mandated head count of every person living in the U.S.

Aside from federal funding, the population counts from the 2020 census impact how congressional seats and Electoral College electors are redistributed among states every 10 years.

Internal documents released as part of the lawsuits contradict Ross' testimony during congressional hearings about the events leading up to his decision to add the citizenship question.

Ross has told lawmakers that his decision was "solely" in response to the Justice Department. The commerce secretary testified that the Justice Department "initiated" the request for a citizenship question to better enforce Section 2 of the Voting Rights Act.

But Commerce Department emails and memos filed in court lawsuits contradict that narrative. They show that Ross and his staff contacted the Justice Department about adding a question months before the department submitted its request to the Census Bureau in December 2017.

In one email, Kris Kobach, the Kansas secretary of state who once helped lead President Trump's now-disbanded commission on voter fraud, contacted the commerce secretary about adding a citizenship question "at the direction of Steve Bannon," the former White House strategist.

KQED reporter Michelle Wileycontributed to this report from San Francisco.

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