* Biden was born in [[Pennsylvania]], a must-win state for Obama where he is weak;<ref>[[Hillary Clinton]] defeated Obama by a wide margin in the [[Pennsylvania]] primary; in August polls show Obama leading McCain by an average of only 5.8% in [[Pennsylvania]] [http://www.realclearpolitics.com/epolls/2008/president/pa/pennsylvania_mccain_vs_obama-244.html RealClearPolitics Pennsylvania Tracking]</ref> | * Biden was born in [[Pennsylvania]], a must-win state for Obama where he is weak;<ref>[[Hillary Clinton]] defeated Obama by a wide margin in the [[Pennsylvania]] primary; in August polls show Obama leading McCain by an average of only 5.8% in [[Pennsylvania]] [http://www.realclearpolitics.com/epolls/2008/president/pa/pennsylvania_mccain_vs_obama-244.html RealClearPolitics Pennsylvania Tracking]</ref> |