Last week Mayor Bloomberg crossed party (and state) lines in favor of a much stronger allegiance: money. Along with City Council Speaker Christine Quinn and actress Lorraine Bracco, the Mayor attended the Democratic National Committee’s annual summer meeting in Chicago, where he rubbed elbows with his former party’s brass and made a case for holding the 2008 Democratic National Convention in the Big Apple. The 2004 Republican Convention drew the ire of many New Yorkers, who resented the GOP influx to the highly Democratic haven. Bloomberg, however, seems colorblind when it comes to party (NYC is also on the short list to hold the RNC gala the same year). Rather than hoisting a candidate to the presidency, as NYC conventions did for both Carter and Clinton, Bloomberg sees only the financial boost. Along with plenty of protest and general bellyaching, the 2004 event reaped about $255 million. And if Bloomberg’s plea somehow falls short, maybe Bracco (star of Goodfellas and “The Sopranos”) knows some thugs who can make the DNC an offer they can’t refuse.