Security Trust Fund Surplus

So the GOP now wants to use the annual surplus in the social security trust fund to fund their vision of personal/private/label-of-the-week accounts. But I thought there was no trust fund? Isn't that what the president argued before? Didn't he once say explicitly, "There is no trust fund -- just IOUs."? So, the GOP wants to use the non-existent surplus of a non-existent fund to fund accounts. Or are they admitting the president was full of it (he certainly has that in surplus)?