Actually Obama has been trying to stop the mortgage fraud with a bill for aggressive enforcement since 2006. Had he been president there would have been far less fraud in 2007-2008 and a number of institutions, including WAMU, Fannie, and Freddie, all of whom are going down now because of vast fraudulent transactions from around 2007, would not be facing imminent demise and perhaps not even eventual demise. Bush on the other hand blocked several state attempts to investigate the mortgage fraud rings starting back in 2003. Under a democrat I agree the loose Fed policy and the tulipmania would probably have still happened but the fraud, and the systemic damage, would have been much less.
Anyway my point was that Bush has drastically weakened our freedom of action *in general* via the massive tax cuts and deficit fueled spending on things like the Iraq War and Medicare D. We now depend on a constant influx of money from foreign central banks to keep the government running and that gives the FCBs, especially China, Russia, and the Gulf States, tremendous influence on our government's policy. This isn't restricted to mortgage funding, it's just that the bubble and its effects are truly huge and this is the first issue important enough for the FCBs to actually wield their power.