Mayor Nutter could regret not pushing for a clearly-needed change in the city's campaign finance law if things break just the wrong way for him next year. Now that Sam Katz has decided not to run in the 2011 Democratic primary, chances are better that millionaire Tom Knox will jump in.

Consider the following scenario: Knox runs, spends a few million on TV ads, bloodies Nutter's image, and loses. Nutter drains his campaign fund battling Knox, then faces the general election with an empty war chest. Because city contribution limits are based on a calendar year rather than an election cycle, the mayor can't raise any new money from donors who gave the max during the primary campaign.That could tempt a Sam Katz or somebody else to enter the fall campaign and run up a money advantage on the mayor. Katz hasn't ruled that out.

I urged Nutter and City Council in past newspaper columns to change the law so that contribution limits are calculated on an election cycle, like practically every other campaign finance law. They didn't do it, I expect because the current system normally favors incumbents. Wonder if it all looks different today.