I forget which President during the 50's or 60's changed the status of the Social Security Fund to General Fund, but they did. The General Fund is the honey pot which pay for so many programs, some useful, others not. President Clinton's claim to fame was balancing the budget. When he did that, shortly after there was an enormous turnover in the House and Senate. Seems that someone saw that huge General Fund, didn't investigate too much, and nabbed it for budget balancing. When the AARP discovered the raid, they were livid, and proved to be the powerful voting block which is still feared.
It used to be 'pay as you go'. They monies you put in were earmarked for you. Now, it's pay for others. Boomers pay for Depression/Twenties. Xers pay for Boomers and Depression/Twenties. Xers, Boomer's kids, and Xer kids pay for Xers, Boomers, and the remaining Depression/Twenties. Boomers are aptly named, since I think their last census data placed them around 80 million (40-60). I think Depression/Twenties is around 48 million (60 and older), Xers around 61 million (25-39) and the rest being 101 million (0-24). These figures were taken from the 2003 Estimates (pdf version)
It could very well be that Social Security could right itself in time, especially if Congress leaves it alone and turns it back into a Special Fund. Since I doubt they'll be able to keep their hands from the till, I still favor personal accounts. If nothing else, it would add an extra measure of security for those unable to buy into IRA or other retirement options by using up to 4% of their payroll taxes, and can will the balance to their own kids or grandkids or cat.
Keep in mind, it wasn't 'just because' that the Democrats lost control of both the House and Senate for the first time in over 40 years back in 1996.