Bush spoke after touring the Bureau of Public Debt in Parkersburg, W.Va., about the $1.7 trillion in Treasury bonds that make up the trust fund...
"There is no trust fund -- just IOUs that I saw firsthand. Imagine, the retirement security for future generations is sitting in a filing cabinet."
As JimPortlandOR, pointed out, that was a direct violation of the Constitution of the United States of America, specifically the 14th Amendment. And no complaining about that Mr. Bush, after all you managed to get Scalia to pull a 14th Amendment argument out of his butt to hand you the 2000 election, in direct violation of your GOP Federalism principles.
From National Archive the original copy of the Amendment XIV of the Constitution...

Ok.. that is hard to read, lets go to the digitally transcribed text itself shall we?
(below the fold)
Let's skip right to the part that was violated by Bush's little remark that should get him impeached:
Section 4. The validity of the public debt of the United States, authorized by law, including debts incurred for payment of pensions and bounties for services in suppressing insurrection or rebellion, shall not be questioned.
In other words, these "IOUs" not only have the backing of the US Government, but are binding under the Constitution of the United States. The Constitution says quite clearly that public debt shall not be questioned yet there is Bush doing just that, in order to push the plan/non-plan scheme of piratizing Social Security.
Rep. Nancy Pelosi's has rightly called Bush to task over this staggering statement, saying "This is the first time that a President of the United States has declared that we, the United States Government, will not put the full faith and credit of the federal government behind the Social Security trust fund. What this President is saying is, we have two kinds of debt. Let's see how we get the debt first. It is in deficit spending, so we have to go borrow in order to keep the government going."
That is a decent statement, but this is not just about the imprudence of Bush's words, or the bad idea it is for finical markets, politically, etc. but that what he is saying is directly un-Constitutional, and the basic premise behind them and what he is in essence suggesting are directly un-Constitutional.
Defaulting on our debts is a direct violation of the United States Constitution, the document that Bush, all of Congress, all of our Judiciary, and every member of our military have all sworn to uphold... where is the outrage?
Where are these people who have sworn to defend the Constitution in stopping this?