Can just anybody run for election in NY? How long has Kerrey been a resident of NYC, or is that even a requirement?
Hell, Hillary only became a resident just prior to the cut-off for registering to vote.
He's president of a university there.
So he's not even a carpetbagger? Then, what's the big deal? In recent history, NY has elected 3 carpetbaggers to the same Senate seat (1964, 1970, 2000).
There is a very distinct difference between Senate races and Mayoral races.
NYC is so staunchly Democratic on a national level that the Republicans who run aren't really Republicans.
Given the choice in a Senate race between an out-of-state carpetbagger Democrat and an in-state somewhat-conservative Republican, NYC (and, usually, the state) will vote for the Democrat. Why? It's more important to not have a conservative than to have a New Yorker, and a Senate seat is a national thing anyway, so it doesn't require you to have
too much of a knowledge of your own state, just enough to get by and to be able to listen to your constituents.
Given the choice in a Mayoral race between an out-of-state carpetbagger Democrat (from Nebraska, who isn't much of a Democrat anyway iirc) and a liberal Republican who's been in NYC all his life, and is the incumbent...New York will choose the Republican. There isn't too much of a difference between the two anyway, and an executive position requires
much more knowledge of the city than a senate seat.
Kerrey won't make it out of the primaries, so it's a moot point anyway.