In response to Bush's repeated warnings, why didn't the Republican-led Congress do anything about it?
Because it is far easier to be a far left Progressive than a Conservative.
As seen by the events leading up to the mortgage/housing/financial meltdown, Here, starting with President Clinton the offer was that they were going to make more loans available to minorities by lowering the standards. Which, if you think about it, is pretty insulting to minorities in and by itself.
It goes on with Progressives offer more and more and easier and easier ways to borrow money. Loans made to people who have no decent credit ratings, a job history or experience being responsible for such a loan.
Then came the NO DOC loans where because people may have trouble verifying their income because much is in tips or cash, this would help minorities too.
So to argue that this was not promoting personal responsibility meant you were racist and how were these people to learn?
That then was the club used to beat Conservatives/Republicans into submission.