The Mayor of New York is one of the most high profile positions in America, arguably more important than the Governor of New York. This is one of the most important cities in the world, and certainly the most important in America. Furthermore, it is the home of the global media, with most of the media's people living here and therefore interested in what happens here. The Mayor of New York has always been a very high profile position, but even moreso in today's global media environment. Whomever speaks for New York, and the things that person chooses to talk about, will have an audience that is quite possibly only rivaled by the presidency in the size of its megaphone.
Democrats have a chance to take back this important seat of authority this year. For 20 years the Mayoral megaphone has been controlled by a couple of autocrats, one of whom is a self-absorbed billionaire. Mayor Giuliani's 'tough on crime' and 'terrorism' focus has been as bad for Democratic messaging as Mayor Bloomberg's focus on making life better for rich people and gun control. Prior to him, Mayors Dinkins and Koch were very much local issues mayors, and were centrists in the mold of acceptable Democrats beaten into submission in the Reagan Era.
Electing a new Democratic Mayor in New York will be an excellent sign of the increasing health of the Democratic Party nationally. Furthermore, electing a left-of-center Mayor would do even more to amplify the message of the progressive wing of the Democratic Party. That person will have a soapbox to move issues. Democrats would do well to take this race as seriously as any that would effect national policy. While the Mayor of New York can't make national policy, that person can lead many other cities' mayors and can command the attention of the national media to focus on issues important to Democrats everywhere.