http://news.yahoo.com/page/election-2008-political-pulse-the-middle
In a nutshell (IMO), McCain needs to convince voters he’s not a “third term for Dubya Bush.” Obama’s tasks (in no particular order): (1) convince voters that his proposed policies (whatever they are beyond “Yes, We Can” or “Si, si puede") aren’t liberalism in a prettier package, (2) convince voters he’s truly bipartisan despite having the most liberal voting record in the Senate, (3) he has the maturity to lead given his resume, (4) convince voters he’s an ordinary American who can empathize with Middle Americans - kind of like what Bill Clinton did in 1992/1996.
