Did the liberals contribute to the tanked economy?

No. You are factually incorrect (don't feel bad, most neocons are). The banks were not "forced" to ignore basic banking rules. They chose to do so because they wanted the refi boom to continue indefinitely. The only way to do that once all of the good credit risks had refinanced, was to start lending to the bad credit risks by coming up with more and more exotic products, such as option ARMS and Interest Only loans. They did it to themselves. Your statement is pure myth.