With the question of who'll fill Sen. Hillary Clinton's seat if and when she's confirmed as secretary of State still unsettled, former New York City Mayor Rudy Giuliani has stepped in to offer his completely objective and unbiased opinion about the qualifications the replacement needs.

In an op-ed published on CNN.com, he writes:

The relationship between the mayor of a large city and a United States senator from that city's state reveals the genius of the U.S. Constitution.

A good senator must perform two tasks simultaneously -- advocate for the interests of his (or her!) state while also helping to shape the direction of the entire country.

As mayor of New York City, I thought of our U.S. senators as New York's advocates in Washington. All of New York's senators during the time I was mayor -- Alfonse D'Amato, Daniel Patrick Moynihan, Charles Schumer and Hillary Clinton -- were effective advocates for New York City.

Each understood the crucial role that New York City plays in New York's economy and in America's economy, as the place that develops the capital that makes the economy work -- the heart that pumps the blood, so to speak.

When New York City is functioning well, the entire economy is functioning well. As we see today, when the city's financial industry is not functioning well, the entire country struggles.

As the nation's biggest city, New York City needs an advocate with the toughness to fight for everything to which we are entitled.

Giuliani also uses the piece to stress the importance of a senator having "a deep understanding of the many formulas that are used to calculate federally distributed aid." Coincidentally, he then goes on to demonstrate his understanding of these formulas and how they're structured.

Unfortunately, the former presidential candidate doesn't offer up any names of people he thinks would be good for the job. But based on his description and his focus on New York City and its mayor, we in Salon's New York bureau have come to the obvious conclusion: Giuliani really, really wants to see Ed Koch get the nod.