Awesome that Social Security is now a central campaign theme. Given that Obama's now ruling out benefit cuts or the raising of the retirement age that leaves... a tax increase.
Obama ruled out benefit cuts or raising the retirement age in the advertisement with which he first raised the issue (in text which flashed on the screen). Your use of "now" suggests that you weren't paying attention.
So yes that leaves a tax increase as oritinally proposed by Obama and as is supported by a majority of Americans according to every poll of the issue.
So what we have is Obama proposed increasing taxes on the richest 6% or earners and roughly 60% of Americans agree with him. What a disaster.
I don't always agree with Black but this is the first time I have been irritated by his willful ignorance.