California Attorney General Xavier Becerra (D) said late Monday he is filing a lawsuit against the Trump administration over its decision to include a question on citizenship in the 2020 census.

"We're prepared to do what we must to protect California from a deficient Census. Including a citizenship question on the 2020 census is not just a bad idea - it is illegal," Becerra said in a statement.

Commerce Secretary Wilbur Ross announced his decision to reinstate the citizenship question in a post on the Commerce website, despite strong objections from Democrats in recent weeks.

The Department of Justice under Attorney General Jeff Sessions has pushed for inclusion of the question, arguing that it would allow the department to better enforce the Voting Rights Act.

Hours before the decision was announced, an op-ed penned by Becerra and California Secretary of State Alex Padilla (D) was published that argued including the question would disproportionately affect California, which has several large immigrant communities.

However, Democrats have expressed concerns that adding the question would result in an inaccurate population count because it would discourage some immigrants from filling out the questionnaire, given the Trump administration's crackdown on those in the country illegally.

Several lawmakers voiced opposition to the announcement on Monday night.

Sen. Bob Menendez (D-N.J.) used the announcement to promote a bill he and other Senate Democrats introduced that would prohibit the census from asking about citizenship or immigration status.

Rep. José Serrano (D-N.Y.) also vowed to present an amendment to eliminate the citizenship question.

Rep. Carolyn Maloney (D), who represents parts of New York City, said Ross "deliberately compromised the integrity of the Census for political purposes."

But GOP Rep. Warren Davidson (Ohio) spoke out in favor of the Trump administration's decision, arguing representation in the House "should be based on citizens, not on residents."