http://www.senate.gov/artandhistory/history/common/briefing/Nominations.htmThe president nominates all federal judges in the judicial branch and specified officers in cabinet-level departments, independent agencies, the military services, the Foreign Service and uniformed civilian services, as well as U.S. attorneys and U.S. marshals. In recent years, more than three hundred positions in fourteen cabinet agencies and more than one hundred positions in independent and other agencies have been subject to presidential appointment. Approximately 4,000 civilian and 65,000 military nominations are submitted to the Senate during each two-year session of Congress. The vast majority are routinely confirmed, while a very small but sometimes highly visible number fail to receive action.
The importance of the position, the qualifications of the nominee, and the prevailing political climate influence the character of the Senate's response to each nomination. Views of the Senate's "proper role" range from a narrow construction that the Senate is obligated to confirm unless the nominee is manifestly lacking in character and competence, to a broad interpretation that accords the Senate power to reject for any reason a majority of its members deems appropriate. Just as the president is not required to explain why he selected a particular nominee, neither is the Senate obligated to give reasons for rejecting a nominee.
Executive branch appointments customarily end with the departure of the president who made them, except for those independent agencies whose officials have fixed terms. Judicial appointments, however, are for life and can be terminated only through the time-consuming congressional impeachment process. Historically, Supreme Court nominations, in great disproportion to their number, have attracted the close attention of senators, the media, and scholars. While the Senate has explicitly rejected fewer than 2 percent of all cabinet nominees since 1789, nearly a quarter of all Supreme Court nominations have failed to be confirmed, their nominations rejected, withdrawn or declined.
The fact is that no matter which party controls the Senate, the vast majority of Presidential judiciary appointees are approved.
Please try to envision the difference between Democratic and Republican appointees. It may be worthy of no more than a shrug to you, but it is life and death to many of us.