The devil is always in the details, and the first devilish detail in the push toward Social Security reform appears to be the question of how to handle the probable transition costs within existing budget rules.  The first shot is a little creative accounting.  From The Washington Post:

Republican budget writers say they may have found a way to cut the federal deficit even if they borrow hundreds of billions more to overhaul the Social Security system: Don't count all that new borrowing.

As they lay the groundwork for what will probably be a controversial fight over Social Security, Republican lawmakers and the Bush administration are examining a number of accounting strategies that would allow the expensive transition to a partially privatized Social Security system without -- at least on paper -- expanding the country's record annual budget deficits. The strategies include, for example, moving the costs of Social Security reform "off-budget" so they are not counted against the government's yearly shortfall.

Although there has apparently been no firm decision on made on how to approach this issue, this statement seems like a model of understatement:

Any accounting mechanism that obscures or minimizes those costs is sure to be controversial.

Over at Vox Baby, Andrew Samwick offers a critical, but thoughtful, analysis.  We, of course, have touched on the financing issues here, here, and here.