Now that Barack Obama has secured the nomination of Democratic candi­date for president, he and his handlers are ramping up their efforts to immunize him from his Chicago past.

We’ve already seen him distance himself from the Reverend Jeremiah Wright, quit Trinity church, criticize Father Pfleger, and downplay his early ties to Tony Rezko.

But Mayor Daley presents a stickier wicket. He’s a big-city boss who has presided over a corrupt, inefficiently run, high-tax government for years. While Obama has mildly disapproved of a few of the most noto­rious scandals, he enthusiastically endorsed the mayor in the last election. They even share David Axelrod as a campaign strategist.