Why did Obama wait until Congress was in recess to appoint Craig Becker to the NLRB?

This past week all 41 U.S. Senate Republicans sent a letter to Obama requesting that he not use the recess to force Craig Becker's appointment to the National Labor Relations Bureau (NLRB) and the U.S. Chamber of Commerce sent a separate letter to the president on behalf of numerous business groups that oppose this disastrous appointment. BUT he did it any way. Becker, if you recall was the SEIU's, Obama's thugs, Lawyer and has worked with ACORN in the past. Why did Obama wait until the recess to make this controversial appointment? Can you imagine how union and management negotiations are going to go with him running the show?