Maine Democrat Rosa Scarcelli suggested that a decision to challenge Sen. Olympia Snowe in 2012 could hinge on whether the three-term Republican is forced to fend off a primary challenge. Scarcelli, the CEO of an affordable-housing agency who ran for the Democratic nomination for governor in 2010, is widely seen as a rising star in her party and says she's very interested in running for public office again. But the 41-year-old also bills herself as a nonpartisan pragmatist who stresses she won't run against Snowe if the senior senator continues to vote as a moderate. "Olympia Snowe in my mind...