(CNN) The House Oversight Committee plans to move ahead on holding Attorney General William Barr and Commerce Secretary Wilbur Ross in contempt of Congress for refusing to comply with their requests for information into a probe about how a question about citizenship ended up on the US Census.

In letters to Barr and Ross, House Oversight Committee Chairman Elijah Cummings wrote, "Unfortunately your actions are part of a pattern. 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 department of the government and across numerous investigations."

"I am writing to inform you that the committee is scheduling a vote to hold you in contempt of Congress as a result of your failure to comply with a bipartisan subpoena issued more than two months ago for documents relating to the addition of a citizenship question to the 2020 Census."

A separate House panel, the Judiciary Committee, has already voted to hold Barr in contempt of Congress for failing to provide the committee with the full unredacted Mueller report and evidence.

In the letters, Cummings said Monday that he would postpone the committee's contempt vote if the Commerce and the Justice Departments produced the materials the committee had previously requested by Thursday.

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