President Barack Obama has vowed to take climate change into his own hands. Now he needs to deliver.
It's been three weeks since Obama made an ambitious speech about his climate change plan.
Executing it will be arduous - the plan is a complicated mix of federal rule changes and permits that's tough to make into a sales pitch. It may be even tougher to put the plan into action.
Some steps have already been taken, including an overhaul of a loan-guarantee program and a reworked proposal for emissions limits on new power plants. Other steps are still to come.
The centerpiece of the plan is limits on existing plants. States take the lead in figuring out how to comply, setting up likely confrontations between Obama and conservative-led states.