In the supporting documents he turned over to Senate investigators as part of his confirmation process, Defense Secretary nominee Chuck Hagel did not disclose at least two recent speeches on the subject of the Arab-Israeli conflict, Fox News has learned.

Obama administration sources and lawmakers said Hagel was required to declare to the Senate Armed Services Committee any "formal speeches" he had given since the start of January 2008.

That Hagel appears not to have declared the two speeches from 2008 could further jeopardize his nomination with Senate Republicans, who have already threatened to block the nomination because they believe Hagel has not turned over enough financial data.

An Obama administration official who has worked with the former Republican senator during his confirmation process maintained that Hagel has gone "above and beyond" the Senate's requirements, by supplying the committee whatever evidence he could find -- prepared remarks, transcripts and the like -- for formal and "informal" speeches.