The buzz in Hudson County this week is about Assemblyman/Union City Mayor Brian Stack’s very public flirtation with a challenge to Senate Majority Leader (and Hudson County Democratic Chairman) Bernard Kenny in the 2007 primary. There has been speculation for months that Kenny, who has been battling prostate cancer and other health issues, had been considering retirement anyway — but some of Kenny’s friends think Stack’s aggressive tone could make a Kenny re-election bid even more likely. Even though Kenny is the incumbent and the party chairman, some Hudson pols say that the ambitious Stack could have the edge in a primary. He is enormously popular in Union City, where he began his political career as a rival of Bob Menendez and then became Menendez’s ally in a fight with Rudy Garcia, and some local pols say that he could carry his hometown by a margin of almost 4-1. Kenny comes from Hoboken, where his strong alliance with Mayor David Roberts could allow Stack to team up with an anti-Roberts Democrat — maybe a backer of former Councilwoman Carol Marsh, who forced Roberts into a runoff in 2005. In that case, West New York — where local leadership will shift in November when Mayor/Assemblyman Albio Sires takes his seat in Congress — might determine the outcome of a 33rd district Democratic primary. Some say Kenny might be at a disadvantage given the traditional North Hudson alliance between Union City and West New York. In Hudson County, where all politics truly is local, power has traditionally rested with the twelve Democratic Mayors. In 1977, the incumbent Democratic State Chairman, James Dugan, lost his bid for a third term in the State Senate when the winner of the Jersey City mayoral election decided to support Walter Sheil instead.