His tightrope walk isn't over.

First he has to get the states onboard, and keep them there, without promising them ambitious renewable energy targets his backbench will hate.

The prime minister also has to keep the right wing of his party happy, which might mean annoying the states with promises on coal or keeping prices down.

And Turnbull has to negotiate with Labor, who are balancing whether to kill off the policy or avoid being the scapegoat for higher power bills.

In a nutshell, there is a reason energy policy has been a complete mess in Australia for more than 10 years.

Former prime minister Tony Abbott is willing to vote against his own party, and the number of MPs he brings with him will be key to Turnbull's success or failure.

Abbott claims a dozen MPs are unhappy with the guarantee, and if they all cross the floor the temptation for Labor to kill the bill will be strong.

But then Bill Shorten will have to decide whether fighting an election on energy policy is a battle he thinks he can win, after the pain Labor has suffered before on that front.

It's a delicate business trying to end a decade of the climate wars, and Turnbull has very little room to make a mistake.

Australian Associated Press