Who deserves the most blame for this fact?
If you frame it as the legislative branch and the executive branch, leaving out the judicial branch, you don't know what is going on.
CO2 regulation is being driven by the courts and to be more specific the SCOTUS decision in 2007. Plus the SCOTUS decision in 2011. Plus the DC Court of Appeals decision in 2012. And to be accurate, SCOTUS has one more decision to make although it is a minor decision.
President Bush, Senator Obama, and President Obama wanted Congress to take the lead, but Congress failed. After which President Obama/EPA moved forward doing what SCOTUS told EPA to do.