Caroline Kennedy is now officially out of the race for the New York U.S. Senate seat vacated by Secretary of State Hillary Clinton.

“I informed Governor Paterson today that for personal reasons I am withdrawing my name from consideration for the United States Senate,” Kennedy wrote in a statement released Thursday.

Why is former frontrunner for appointment to the seat no longer seeking it? all indications are that she did not want to be passed over by Paterson, who has decided to appoint someone else.

So which someone will it be?

Leading in the speculation game at this point in New York Attorney General Andrew Cuomo, a former member of Bill Clinton’s Cabinet who knows Washington well and who Paterson fears as a potential rival.

Also in the running are New York Democratic House members Kirsten Gillibrand and Carolyn Maloney. Selecting either of them would score Paterson points with women as he prepares to bid for reelection in 2010. Or Paterson could try to help himself with suburban or upstate voters by selecting Nassau Country Executive Tom Suozzi, Long Island Congressman Steve Israel or Buffalo-area Congressman Brian Higgins.

Or… or… or…

The speculation game will go into overdrive now that Kennedy has quit, and every prospect will be analyzed not with regard to his or her potential contributions to the Congress but with regard to his or her potential benefits for Paterson.

That’s what is wrong with allowing senators to be appointed by governors. If political and personal considerations by governors may not always be Rod Blagojevich ugly, but they are always ugly.

Governors appoint senators with an eye toward helping themselves and their friends. And the appointed senators become frontrunners for vacant seats. From a small “d” democracy standpoint, the process is doubly compromised.

If Paterson wanted to do something honorable — and, frankly, politically smart — he would reject the compromises and do right by New York and the Senate.

How could he do that? By appointing a Cuomo to the Senate.

But not Andrew Cuomo.

Paterson should appoint one of his predecessors in the governor’s office, Mario Cuomo, as a placeholder senator who can occupy the seat until a new senator is elected by the voters of New York in 2010.

Mario Cuomo, a man of government and a Constitutional scholar, would be an ideal senator in this moment of national redirection and renewal. To an even greater extent than his son, Mario Cuomo could hit the ground running in Washington, maintaining Clinton’s strong office and representing New York well while at the same time serving an elder statesperson on key committees.

Just imagine Mario Cuomo, the man who should have been the chief justice who administered the oath to President Obama on January 20 (and who would have gotten the words right), serving on the Senate Judiciary Committee. Imagine this former governor joining in the debates about how to stimulate state economies. Imagine this moral force adding his voice to discussions about remaking our failed foreign policies.

The United States should not have appointed senators. But if one must be appointed from New York, then there is a right choice: Mario Cuomo.