The Justice Department will ask President Trump to invoke executive privilege over census documents if a House committee follows through on its plan to vote to hold Attorney General William Barr and Commerce Secretary Wilbur Ross in contempt. The committee wants material related to the addition of a citizenship question to the 2020 census.

Assistant Attorney General Stephen Boyd wrote a letter to Committee Chairman Elijah Cummings saying that some of the materials sought by the committee are protected from disclosure by the deliberative process, attorney-client communications or attorney work product components of executive privilege. The letter also claimed the committee was trying to bar Assistant Attorney General for the Civil Rights Division John Gore from testifying without agency counsel present.

Boyd accused the committee of failing to follow the mandated accommodation process that's supposed to take place between the Justice Department and the committee "by declining to negotiate" over the scope of the subpoena and by not recognizing "legitimate executive branch interests." He also said the committee had made a "premature decision" to hold a contempt vote and because of the vote, Boyd said "the Attorney General is now compelled to request that the president invoke executive privilege" regarding material subject to the subpoenas of both Barr and Ross.

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He requested that the committee temporarily halt the issuing of the subpoenas and delay its contempt vote until the president makes a determination on the materials the committee wants.

Critics of the citizenship question argue that adding such a question could deter non-citizens from self-reporting, which in turn could lead to an undercount of primarily Hispanic voters in Democratic states. This could affect congressional apportionment and benefit rural, more Republican states.

This suspicion has been bolstered by the revelation that a Republican expert on gerrymandering had advocated for adding the question in order to benefit "Republicans and Non-Hispanic Whites." A report released last week found that the census could undercount more than 4 million people, particularly in Latino and African American communities.

The addition of the question is also being challenged in the Supreme Court. The Court is expected to rule on the legality of the addition this month.

Cummings sent letters to Ross and Barr earlier in June, informing the two cabinet officials that the Democratic-led panel was in the process of scheduling contempt votes against them.

"Your actions are part of a pattern," Cummings wrote in both letters. "The Trump Administration has been engaged in one of the most unprecedented cover-ups since Watergate, extending from the White House to multiple federal agencies and departments of the government and across numerous investigations. The tactics of this cover-up are now clear."