Hillary Clinton, Scott Walker, and the Future of Obama's Climate Plan

President Obama is rolling out the tentpole of his climate action plan — and its future is out of his hands.

The first carbon pollution standards for power plants will force the power sector to cut emissions by 32 percent compared to 2005 levels by 2030. While it's Obama's rule through and through, the long timeframe means it won't bear fruit until he's out of office. States won't have to start telling the EPA how they will comply with emissions targets until September 2016 at the earliest, the tail end of Obama's presidency, and don't have to start implementing them until 2022.

And given the certainty of lawsuits, the complicated nature of the work that EPA and states will have to do, and attacks from Capitol Hill, nothing is set in stone. While the current White House has a key role to play in getting state plans in shape and waving the veto pen against attacks from congressional Republicans, here's our list of the people who will determine the future of Obama's climate plan:

Hillary Clinton

The leading Democratic presidential nominee, Clinton has only recently started rolling out her energy-and-environmental agenda. But a key component will be her promise to keep the Clean Power Plan on the books and even expand it. In a statement Sunday, Clinton said she'd defend it against "Republican doubters and defeatists" who "won't offer any credible solution" and "don't want one."

Clinton has already announced a plan to have the U.S. generate enough renewable energy to power every home within a decade of the start of her presidency, along with having more than a half a billion solar panels installed across the country within her first term. That would scale up renewable power beyond what's likely deployed under the climate rule.

Democratic challengers Bernie Sanders and Martin O'Malley also have said they would protect the climate rules and step up the fight against climate change beyond what Obama has proposed; O'Malley has pitched a plan to get the nation to entirely renewable power by 2050.

Jeb Bush, Donald Trump, Lindsey Graham "¦

On the flip side, should a Republican win the White House, expect an immediate effort to find ways to curb the Clean Power Plan. Even the candidates who say they are concerned about man-made climate change, such as Jeb Bush or Lindsey Graham, don't think that a massive regulatory scheme is the right way to get at the problem. In a recent interview, Bush said the EPA rules would be "irresponsible and ineffective" and would do "virtually nothing to address the risk of climate change."

So how could a Republican president undo the climate plan? States will be submitting plans in the fall of 2016 but can request up to a two-year extension, meaning submissions could be coming under a new president. A Republican administration could relax the implementation and review process to allow, say, coal-heavy states to lean on weaker plans. The legal challenges to the rule could also offer a future administration a prime opportunity to knock it down — should a court overturn any piece of the rule, the EPA could rewrite it to its liking, much the way the Obama EPA retooled George W. Bush-era regulations on air pollution that crosses state lines.

Mitch McConnell

The Senate majority leader has taken the EPA rule head on, pushing a plan that would have governors simply opt-out of compliance, saying that the rule is illegal and would cause more harm than good. When the Supreme Court ruled against the EPA over standards on mercury pollution in June, McConnell said it was only more proof that governors should not "subject their states to such unnecessary pain before courts have even had a chance to weigh in." Whether or not the opt-out plan would work (critics have pointed out that even McConnell's home state of Kentucky is working to meet the standards), McConnell is still armed with an array of weapons to use against the rule.

Expect both chambers to go hard after the regulations when they return in September. The House has already passed a bill from Rep. Ed Whitfield that would let governors opt out and delay implementation of the rule until all legal challenges are settled. Sen. Shelley Moore Capito has a similar bill and she told National Journal before the rule was released that she is eager to move it as soon as possible. And leaders in both chambers have said they will attempt to use the Congressional Review Act to express their disapproval — although that avenue has never been successful against an EPA regulation.

Potentially the best tool to Republicans will come when Congress hashes out a budget in the fall. McConnell used his perch on the Interior and EPA appropriations panel to insert opt-out language into that agency's spending bill. The House likewise had a rider on the rule and would have slashed funding for the EPA in a bill that was ultimately pulled from the floor over an unrelated Confederate flag amendment. Given the anger over the rule, Republicans are sure to try to include some language attacking it in a budget or continuing resolution — one of many major fights they will have with Obama leading up to the Sept. 30 end of the fiscal year.

Mary Fallin, Mike Pence, Scott Walker, and other GOP governors

McConnell's opt-out plan depends on having governors play along, and he may have plenty of followers joining him. Oklahoma Gov. Mary Fallin in April issued an executive order directing state agencies to not write a compliance plan. Wisconsin's Scott Walker, Indiana's Mike Pence, and Louisiana's Bobby Jindal are also among the governors who say they anticipating opting out of the rule. For presidential contenders such as Jindal or Ohio's John Kasich (who has not said what he'd do with the climate rule), it's an easy signal to voters of an anti-regulatory stance.

The EPA, anticipating resistance from states, is writing a federal implementation plan that would be applied to states that either do not submit their own plan or offer one that does not pass muster. Such a plan is certain to open up a fresh lane of legal challenges, with states arguing that the federal government should not try to impose a one-size-fits-all scheme.

Anthony Kennedy

How much do opponents want to litigate the Clean Power Plan? Even when a federal court rejected a lawsuit by utilities and states in June for being premature because the rule was still in its proposed state, challengers still appealed to keep the pressure on. Now that the rule is officially out, challengers will have plenty of chances to take the EPA to court, with industry groups siding with former Obama mentor and Harvard University professor Laurence Tribe as their star litigator. Among the possible legal threads would be the EPA's constitutional authority over states, whether it can regulate carbon dioxide from power plants already being regulated for other pollutants and the legality of the imposition of a federal plan for states that opt out.

Greens have said they are confident that the EPA has the authority to impose restrictions on carbon dioxide and has written a legally sound rule, especially given the agency's track record in court. But challengers are likely to seek every legal avenue to knock down the rule, or at least put a stay on it to give states some relief. The ultimate destination, then, is likely the Supreme Court, where all eyes will once again fall to Justice Anthony Kennedy, the swing vote on most environmental cases and who has shown a willingness to side with EPA's authority.