Obama advisers and other Democrats see a Santorum whose record, writings and statements, particularly on social issues, will be used to portray him as far too conservative for many voters. His record, they say, could make Santorum anathema to suburban swing voters, especially women. That view is shared by some Republicans and independent analysts.

“They [Democrats] would brutalize him on social and cultural issues and present him as so far out of the mainstream as to be radical,” said G. Terry Madonna, director of the Center for Politics and Public Affairs at Franklin & Marshall College and a leading pollster in Pennsylvania. “The analogy would be Barry Goldwater” — the 1964 GOP nominee who suffered a landslide defeat.

Santorum’s advisers recognize that he has entered a new phase in his campaign, and they see the obstacles ahead. They argue that a full and fair reading of his record reveals a more attractive profile of the former senator. But they acknowledge it is up to Santorum and his campaign to explain that record and allay concerns about his ability to run competitively in November.