Pozen's Plan

A summary:

Under the proposal, first developed by Robert C. Pozen, an investment executive, benefit cuts would be imposed gradually on future retirees. The cuts would fall most heavily on people at upper income levels. The cuts would be less, but still substantial, for middle-income workers. Low- income people would suffer no benefit cut at all. Politically, the plan has the advantage, in the White House's view, of being attractive to moderate Democrats by making the system more progressive.

Here's the problem with this. If you make social security a program that only benefits the poor, public support for it will rapidly decrease (like medicaid) and eventually you'd see the entire program phased out. This aggression will not stand.