which is a bigger liability

[Politico]

In Romney's defense, he was running against a Kennedy in Massachusetts.

In Santorum's defense, he was running against a Casey in Pennsylvania.

Ted Kennedy was, for better or worse, a national icon. Bob Casey is just the bald son of a famous Governor. Nobody outside of Pennsylvania knows him.

Furthermore, Romney's '94 campaign was almost solely funded by his own pocket. Santorum was the darling of K Street, and even those bucks couldn't keep him from joining George McGovern among the ranks of incumbent Senators who lost by nearly twenty points.

[Politico]

Santorum's. Romney lost in Massachusetts to a Kennedy (and what's more, the one who was basically the public face of American liberalism for 30 years).

Exactly. The only people on here who would argue otherwise are clearly too young to understand how big Ted Kennedy was with regards to American liberalism. Ted Kennedy was to the liberal wing of the Democratic Party what Ronald Reagan was/is to the conservative wing of the Republican Party.