Bush pushed for economic reform pertaining to subprime mortgages in '03. McCain pushed for economic reform pertaining to subprime mortgages in '05 and again in '07, but was out-voted. Barack Obama pushed the opposite way. He pushed to force banks to give low-income, high-risk lenders mortgages AND he made mone off Fannie Mae, and still is making money from his friends from Fannie Mae in campaign donations.
Watch the video, but be prepared to pause it. It goes fast. It's 10 minutes and it's VERY worth it.