How Did George Bush cause the recession?

I think his administration could have pushed the issue of needing to regulate Fannie & Freddie harder back when they raised the first flag about it in 2001. Given that the 2003 warning by the administration was also blown off, they should have launched an all out crusade over it when it came up again in 2005. In that respect, I do believe the administration was weaker than it should have been. I'm not saying they could have prevented the recession altogether, but the blow could have been softened if they'd been more forceful with Congress about addressing the impending disaster.