Story highlights Nominees have to obtain OGE's certification of their financial disclosure reports

The letter was released by Schumer's office

(CNN) Several of President-elect Donald Trump's Cabinet nominees have still not been properly vetted less than one week before hearings begin on Capitol Hill, the Office of Government Ethics said in a letter to Democratic senators Friday.

"The announced hearing schedule for several nominees who have not completed the ethics review process is of great concern to me," wrote Walter M. Shaub, director of the Office of Government Ethics, in a letter to New York Sen. Chuck Schumer and Massachusetts Sen. Elizabeth Warren. "This schedule has created undue pressure on OGE's staff and agency ethics officials to rush through these important reviews."

Shaub, who was appointed by President Barack Obama, said his office hasn't received initial drafts from some nominees.

"I am not aware of any occasion in the four decades since OGE was established when the Senate held a confirmation hearing before the nominee had completed the ethics review process," he said.

However in 2001, the Senate Health, Education, Labor and Pensions Committee held a confirmation hearing on Education Secretary Rod Paige eight days before receiving his OGE paperwork.

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