There is a very interesting op-ed about Social Security in today's Wall Street .  It is written by Thomas Saving, who served two terms as a public trustee of the Social Security and Medicare Trust Funds.  Saving states that making Social Security payments will not have any impact on the legal value of the total public debt.  Here is the money quote:

By law the Treasury is bound to redeem any bonds presented to it by the Social Security Administration.  And when the Treasury does, total government debt subject to the debt limit falls by the amount of the redemption- thus freeing up the Treasury's ability to issue new bonds equal in amount to the redeemed Trust Fund bonds...  Therefore, meeting Social Security obligations in August, September and all future months in this fashion would add nothing to the gross government debt subject to the debt limit.

So then, the budget gap is really as follows.  Total scheduled expenditures are about $307 billion, while receipts are estimated to be $172 billion.  But the expenditures include roughly $50 billion for Social Security.  Therefore the REAL accounting gap is $85 billion, NOT $135 billion as most people have stated.  See here, for example.

Note also how disingenuous Obama's statement about not being able to send out Social Security checks is.