Most of those who pushed the lowering of mortgage lending standards were Democrats-- notably Congressman Barney Frank and Senator Christopher Dodd, though too many Republicans went along.
At the heart of these policies were Fannie Mae and Freddie Mac, who bought huge amounts of risky mortgages, passing the risk on from the banks that lent the money (and made the profits) to the taxpayers who were not even aware that they would end up paying in the end.
My question is why did Freddie and Fannie do this?
Here's an article provided by Frank Rambo:
http://www.clevelandfed.org/research/commentary/2009/0509.cfm
Here's a site by Liberal BS Filter that deals with some of these issues:
http://liberalbsfilter.com/liberal-economic-myth.html
Here's an article:
Three Ways The CRA Pushed Countrywide To Lower Lending Standards