From the subscription-only Wall Street Journal.

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Sen. Charles Schumer of New York, chairman of the Senate Democrats' campaign committee, says Social Security will be a "huge" issue in next year's elections, but especially against Mr. Santorum. "Whether you're young, old or middle-aged, people don't like the president's Social Security plan," Mr. Schumer says. "And after the president himself, Santorum is its lead proponent, spokesperson and advocate." [...]
"In the world we live in, it's almost impossible to predict what races will be about this far out," says John Brabender, a Santorum campaign consultant since the Republican first ran for the House in 1990, and godfather to one of the senator's six children. "If the elections were held anywhere today, I don't think Republicans anywhere would do particularly well," because of Social Security, as well as Republican House Leader Tom DeLay's ethics problems and Republicans' unpopular and unsuccessful intervention to keep Terri Schiavo alive.
This may very well become one of the costliest races in Senate history, but there's no way Santorum survives. Pennsylvania has the second largest number of seniors in the country, after Florida, and they're not liking what they're seeing in privatization.