A McCain-Palin ad, in turn, blames Democrats for the mess. The ad says that the crisis “didn’t have to happen,” because legislation McCain cosponsored would have tightened regulations on Fannie Mae and Freddie Mac. But, the ad says, Obama “was notably silent” while Democrats killed the bill. That’s oversimplified. Republicans, who controlled the Senate at the time, did not bring the bill forward for a vote. And it’s unclear how much the legislation would have helped, as McCain signed on just two months before the housing bubble popped.