Why is it not only single Dem ever called for investigations of Fannie or Freddie ?

Democrats like to use the "scapegoat " of Republican deregualtion but if it was derugualtion that was to blame why didnt Dems call for more regulations ? They didnt not once ever ! Ohhh ya Barrack dashes off a hurried letter to the Treasury Secretary a month before the meltdown just to cover his behind thanks BO for all your help there buddy !