Through his own doing, Obama is without a congressional mandate and his use of "executive order" has its [serious] limitations.

Because of his overtly belligerent attitude,  Obama is without a congressional mandate.  His only course of action remaining,  as a tool for continued governance, is the "executive order."  The problem with the power of an  "executive order" is that it is neither permanent as a matter of law nor immediate.  If he turns to climate change as that which will mark his legacy for the second term, but must resort to a dictatorial use of  "executive order" to accomplish that legacy,  his second term presidency will be seen as a failed experiment in combative leadership,  and will ultimately define him as the novice/inept leader he has proven to be up until now.  

The excerpt below,  taken from The Hill,  gives the readership a little understanding into the problem of "legacy building via dictatorial demand,"  a problem (for Obama) that may prove to be overwhelming.  

In short,  "executive order" is not the panacea Obama may think it is.  

From The Hill:  President Obama has a chance to craft a second-term legacy on
climate change even as the rest of his agenda runs aground in Congress.    Gun control legislation is dead; immigration reform is on life support; and reaching a fiscal deal with Republicans appears to be a long shot.   To make matters worse, what was supposed to be his signature first-term achievement — ObamaCare — is suffering from a disastrous rollout.  . . . . .   But there’s one thing that’s going right for Obama: Executive action on climate change is moving full-speed ahead at the Environmental Protection Agency (EPA).  . . . .  

Princeton University professor Julian Zelizer said the push on climate change through executive action could shape Obama’s legacy — but only to a point.

“There are limits to what it will mean to his presidency,” said Zelizer, who teaches history and public affairs.  One problem facing Obama is that some of the new EPA regulations might not be settled by the time he leaves office.   “[Administrative actions] don’t have the same kind of impact in defining a president as big legislative accomplishments and they are more susceptible to being overturned,” Zelizer said. “The next president can change them. That’s always the problem.”

The president in June told the EPA to release draft federal emissions rules for existing power plants in June 2014 and complete them a year later. Then states would have until mid-2016 to submit plans to the EPA to implement the mandate.

But the coal and power companies are certain to challenge the rules in the courts.

“Even if EPA is able to stay on schedule and sign the final ... rule by June of 2015, it is very unlikely that litigation over the rule will be resolved before the President leaves office,” said Jeff Holmstead, a partner at Bracewell & Giuliani who was the top air pollution regulator at the EPA under President George W. Bush.

Holmstead noted that after states submit their plans, the EPA must decide whether to approve or disapprove them.  “At that point, there is likely to be litigation over EPA's decision,” said Holmstead, whose firm represents power companies that use coal and refiners that oppose EPA regulation, among other clients.   Holmstead predicted there would be “years of litigation” on the existing power plants rules, involving “possibly as many as 50 different lawsuits in every U.S. Circuit Court in the country.”  (You will want to finish reading this article, here).