President Barack Obama applauds in the East Room of the White House in Washington, Monday March 18, 2013, where he announced he would nominate Thomas E. Perez, right, for Labor Secretary. (AP Photo/Jacquelyn Martin)

President Barack Obama announces his nominee for Secretary of Labor, Thomas E. Perez, in the East Room of the White House in Washington on Monday March 18, 2013. (AP Photo/Jacquelyn Martin)

White House press secretary Jay Carney gestures as he speaks during his daily news briefing at the White House in Washington, Monday, March, 18, 2013. (AP Photo/Pablo Martinez Monsivais)

Thomas E. Perez, President Barack Obama's nominee for Labor Secretary, listens at right as the president makes the announcement, Monday, March 18, 2013, in the East Room of the White House in Washington. (AP Photo/Pablo Martinez Monsivais)

Thomas E. Perez, President Barack Obama's nominee for Labor Secretary, speaks in the East Room of the White House in Washington, Monday March 18, 2013, where the president made the announcment. (AP Photo/Jacquelyn Martin)

President Barack Obama and his nominee for Labor Secretary, Thomas E. Perez, leave the East Room of the White House in Washington, Monday March 18, 2013, after the president made the announcement. (AP Photo/Jacquelyn Martin)

Thomas E. Perez smiles at right as President Barack Obama announces he will nominate Perez for Labor Secretary, Monday, March 18, 2013, in the East Room of the White House in Washington. (AP Photo/Pablo Martinez Monsivais)

President Barack Obama talks with his nominee for Labor Secretary, Thomas E. Perez, during a announcement, Monday, March 18, 2013, in the East Room of the White House in Washington. (AP Photo/Pablo Martinez Monsivais)

FILE - In this Thursday, May 10, 2012 file photo, United States Assistant Attorney General Thomas Perez, left, is joined by Deputy Assistant Attorney General for Civil Rights, Roy Austin, as Perez announces a federal civil lawsuit against Maricopa County Sheriff Joe Arpaio during a news conference in Phoenix. The White House says President Barack Obama on Monday, March 18, 2012 will nominate Perez to head the Labor Department. (AP Photo/Ross D. Franklin, File)