Reporting from Washington -- The Northeast's dwindling cast of Senate Republicans has Democrats circling Arlen Specter's seat in Pennsylvania, convinced the party is well-positioned to make a competitive race out of the 2010 election. Leading the pack of prospects -- at least in celebrity -- is Chris Matthews, the MSNBC "Hardball" host and a former Capitol Hill Democratic staffer. The Philadelphia native has been toying with a run for months, and this week he sat down with state Democrats to discuss the prospect of taking on the five-term GOP senator. Others considered in the mix include Rep. Joe Sestak, who...