Obama has only 43% of his staff that needs to be vetted by the Senate.

HOW MANY CZARS DOES HE HAVE???
Of more than 500 senior policymaking positions requiring Senate confirmation, just 43 percent have been filled......................
No matter how the counting is done, though, hundreds of senior positions remain empty with 15 percent of Mr. Obama’s term over. While appointments linger, those jobs are generally filled with acting officials — and the White House says that has not slowed its ability to effect change, reports the NY Times

An answer as to why can be seen at Hotair. They say, "However, concerns that Obama’s appointees might be so problematic that even the complacent Senate might object would explain the dozens of “czars” Obama has installed — some with ethical clouds, all undermining the Senate’s constitutional role advice and consent."