France on Monday led a push at the United Nations to keep the United States in the Paris climate agreement, as Donald Trump's administration insisted it was not changing gears.
Gary Cohn, the chief White House economic adviser, reiterated Trump's opposition to the landmark accord as he met over breakfast with officials from other major economies at the start of the UN General Assembly, an annual week of diplomacy.
But French Foreign Minister Jean-Yves Le Drian, whose government has made preserving the agreement reached in the French capital in 2015 a top priority, held out hope.
"We take note of President Trump's statements on not respecting it, but for the moment no action has been taken and we can still hope to persuade him," he told reporters.
"We have to make sure that international pressure is strong and that we do not stop the agreement from coming into force," he said, noting that French President Emmanuel Macron has called a climate summit for December 12 in Paris.
The Trump administration has sent out mixed messages on the Paris deal in recent days.
European officials suggested after a climate meeting in Montreal on Saturday that Washington might be ready to re-engage with the pact.
That prompted a firm pushback from the White House which insisted its stance was unchanged -- only for Secretary of State Rex Tillerson to assert a day later that the US was studying ways to cooperate with other countries on what, he said, "is still a challenging issue."
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Trump, whose Republican Party has strong ties to the fossil fuel industry, has said that the Paris agreement is unfair to the world's largest economy.
In pulling out, the United States would be the only country outside the Paris accord other than war-torn Syria and Nicaragua, which had pressed for a stricter deal.
The agreement, championed by Trump's predecessor Barack Obama, calls for countries to set their own plans with a goal of keeping global warming over this century under two degrees Celsius (3.6 Fahrenheit) from pre-industrial levels.
UN Secretary General Antonio Guterres warned Monday that there was no time to spare, estimating that more than 20 million people have already been displaced by floods, storms or other extreme weather linked to climate change since 2008.
"In Paris, we rose to a global challenge. Now we have an even bigger challenge: raising ambition and staying on course," Guterres said.
But in the wake of Trump's move, the UN chief focused on action by non-state players such as businesses and regional governments.
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Governor Jerry Brown of California, the most populous US state, took part in a meeting called by Guterres and has called a meeting of non-governmental players on climate change for next year.
"America is not run by Donald Trump," Brown said.
"We are a country of diverse power centers, and mobilizing those power centers that are not controlled by the president is still a very worthwhile goal and very powerful," he said.
Former New York mayor Michael Bloomberg, who is serving as a UN special envoy on cities and climate change, joked of the US position: "We're in, we're out, we're in, we're out."
But Bloomberg said that, even without Trump's support, the United States could still meet Obama-era goals on reducing the carbon emissions behind climate change.
Cohn, a former Goldman Sachs investment banker, at his meeting with officials of major economies discussed the role of US energy technology in both economic growth and lowering carbon emissions, a White House official said.
The official said that Cohn made clear during the breakfast that the United States is "withdrawing from the Paris agreement unless we can re-engage on terms more favorable to the United States."