Barack Obama will defend the Paris climate change agreement and forge ahead on his environmental agenda until his final days in the White House, according to analysts. And there is very little Obama's opponents in Congress can do to stop him - unless they win the elections and install a Republican in the White House in 2017.
Republicans' initial attempts to derail the Paris agreement fell flat, with Congress failing to deliver on threats to cut off climate aid to developing countries or block the deal.
But Obama still has a fight on his hands - from lawsuits and new resolutions intended to undermine the Paris agreement - during an election year which could give an unusual degree of attention to climate change.
After an epic year in 2015, with the Paris climate agreement in December and the final release of rules cutting carbon emissions from power plants in August, Obama is expected to keep pushing his climate agenda in 2016, racing to roll out new regulations on the oil and gas industry before leaving office.
"My sense is that when it comes to the climate issue, broadly, the president will look for every opportunity to advance his agenda," said David Sandalow, a fellow at the Center on Global Energy Policy at Columbia University, and a former Obama Administration official. "He has been relentless on this issue and with results."
Before the Paris summit, Republicans in Congress vowed repeatedly to overturn Obama's plan to cut carbon emissions from power plants, moving two resolutions to strike down the rules. As 150 leaders converged on Paris for the start of the global warming negotiations, congressional Republicans threatened repeatedly to undo the agreement in Congress, and to block climate aid Obama had pledged to developing countries.
The US earlier this year committed $3bn to help developing countries cut carbon emissions and move to cleaner fuels.
The Republican presidential candidate Ted Cruz told the Senate science committee there was no evidence climate change was occurring.
But by 18 December, when Obama left for his vacation in Hawaii, Republicans had failed to make good on any of their threats. The president used his veto to block the resolutions against his clean power plant rules, and the budget deal passed by Congress included a first tranche of $500m Obama had promised for the Green Climate Fund.
The budget deal also extended tax credits for the solar and wind industries - which were seen as a significant boost for the renewable energy sector.
That leaves the Republicans with diminishing options to try to block Obama's climate plan - unless, of course, they take the White House.
"Any country can withdraw from an international agreement," Sandalow said. "That would hurt the US image and interests around the world. We saw 150 heads of state go to Paris and not a single one of them contested the science on climate change," he went on. "The global consensus on the need to address this issue is very strong."
But it is not shared by current Republican leaders.
In 2016, one key preoccupation for the White House will be defending the Environmental Protection Agency rules cutting power plant carbon emissions from lawsuits brought by 27 states, industries and other groups.
The US court of appeals for the District of Columbia circuit will decide in early 2016 whether to halt the rules, while the lawsuits go ahead.
Meanwhile, Republicans in Congress say they will seek to block the US from committing to a climate fund for developing countries in 2017 - a key underpinning of the Paris agreement.
Administration officials said Obama would look to use his executive powers as president once again to cut US climate pollution in line with US commitments under the Paris agreement.
The agreement for the first time commits all countries to curb climate pollution, with a goal of limiting temperature rise to well below 2C and achieving net-zero emissions by the second half of the century.
Under the deal, Obama promised to cut greenhouse gas emissions by up to 28% below 2005 levels by 2025. But the US needs to undertake further cuts if it is to have any chance of meeting that target.
The White House adviser Brian Deese suggested officials were exploring new rules to plug methane leaks at oil and gas refineries and ageing natural gas pipelines.
Methane is the second most prevalent greenhouse gas after carbon dioxide, and 80 times more powerful a warming agent in the short term.
Deese told a seminar hosted by the New Republic that officials were looking at expanding rules cutting methane from frack sites. "If we want to get to that goal, we have to do more on the policy side," Deese said.
The administration is expected to expand energy efficiency rules.
There is also a strong push from billionaire activist Tom Steyer and others to get candidates talking about climate change on the campaign trail.
"This will be the first election where climate change is one of the top two or three issues. I believe that is very possible," said Paul Bledsoe, a consultant who served in Bill Clinton's administration. "It is up to Hillary Clinton, if she is the nominee, to make it an issue, particularly in key states like Florida, Colorado, Nevada and New Hampshire. There are a couple of states where climate change could become a significant issue."
The idea, according to campaigners, is to keep climate change on the public stage, and so avoid a repeat of the situation that doomed the last international climate change agreement: the 1997 Kyoto protocol.
George W Bush formally withdrew from the Kyoto protocol, undermining the treaty. Obama administration officials believe they are on firmer ground with the Paris agreement.
Unlike Kyoto, the Paris deal requires all countries to cut climate pollution - and not just industrialised countries - removing one of the main objections of Republicans.
In the last three years, Obama has also worked hard to reach agreements with China, India, Brazil and Mexico to cut their emissions. Obama invested enormous political capital in the agreement, telephoning the leaders of China, India, France, Brazil and other countries in the final hours to seal the deal. The White House is expected to continue pursuing climate initiatives with rising economies.
Obama is also counting on business leaders, such as Bill Gates and Mark Zuckerberg who have pledged to invest billions to promote green energy.
Those efforts are unlikely to deter Republicans in Congress. So far, however, Republicans have been unable to deliver on their threats to defeat Obama's climate plan or derail the Paris climate talks.
By his year-end news conference, Obama was confident his climate agenda would survive once he leaves the White House.
"Do I think there's going to be a lot of noise and campaigning next year about how we're going stop Paris in its tracks?" he asked. "There will probably be a lot of noise like that. Do I actually think that two years from now, three years from now, even Republican members of Congress, are going to look at it and say that's a smart thing to do? I don't think they will."