Democrats pressed Commerce Secretary Wilbur Ross Thursday on his decision to add a citizenship question to the federal census, alleging that prior testimony by Ross was disproven by newly-discovered information.

"We gave very serious questions about whether Secretary Ross was truthful when he appeared before Congress last year and testified on there occasions that he added the citizenship question on because the Department of Justice requested it," said Oversight and Reform Committee Chairman Elijah Cummings, D-Md.

Cummings said that new documents instead showed that Ross was "choreographing" efforts behind the scenes to add the question, "Is this person a citizen of the United States?" to the census, the government's once-a-decade counting of U.S. residents. He pointed to a summary of an interview with a Justice Department Civil Rights attorney who said he received a hand-delivered memo from the Commerce Department in the fall of 2017 regarding the citizenship question.

The contents of the 2017 Commerce memo have not been released by the administration, though the committee has requested it. Cummings asked Ross whether the "secret memo" included the "real reason" the administration wanted to add the question.

Ross said he did not know what was in the memo and added that he wasn't even certain that such a document actually existed. "I don't believe that there is anything in evidence that my staff delivered a message of that sort," he said, adding later that he stood by his earlier testimony that adding the citizenship question was based on a recommendation from the Justice Department.

"It hard for us not to conclude at the very least that you are obfuscating your role and what you said before this committee," Rep. Mark DeSaulnier, D-Calif., said.

Democrats allege that adding the question is discriminatory and could damage the census by causing illegal immigrants to answer untruthfully or avoid the census altogether. The Trump administration argues it is necessary to get accurate information about the nation's population. The U.S. Supreme Court is currently hearing a case about the propriety of including the question.

Republicans expressed bafflement over the fact that hearing was being held at all. Rep. Mark Meadows, R-N.C., noted that the citizenship question was asked in the 2000 census overseen by the Clinton administration, and there was no reason to be there was any "nefarious purpose" to it.