PARIS — It is going to be O.K. That was the message from 10 Democratic members of the United States Senate who attended the Paris climate talks to reassure other countries that Washington would do its part.
Of the 195 countries taking part in the talks, the United States seems to be a special case. Not only is it the world’s largest economy and the second largest emitter of the greenhouses gases that are warming the planet — it is also the only major power here for which it is unclear whether the government speaks with one voice.
European and Asian negotiators have expressed confusion — if not outrage — over the same questions that Washington is asking: Where is the line defining the limits of executive regulatory powers and legislative authority? The question involving environmental regulations has made its way to the United States Supreme Court.
The negotiators know that Congress is governed by Republican majorities that are hostile to President Obama’s agenda. They know that whatever accord is reached in Paris will not be regarded as a treaty under American law, because Mr. Obama would not be able to secure Senate ratification of a formal treaty.
They say they fear that a future Congress or president could undo Mr. Obama’s clean-energy plan, his regulations capping pollution from power plants and his pledge to work with China, the world’s largest carbon emitter, to curb emissions.
The Democratic delegation, led by Senator Benjamin L. Cardin of Maryland, urged the other leaders not to worry.
“I’m here to tell you that the United States’ leadership and its people fully support all the work that has been done here,” Mr. Cardin said at a gathering of mayors from around the world, at City Hall in Paris. “The United States will continue its leadership and carry out its commitments.”
Senator Jeff Merkley of Oregon called global warming “the moral challenge of our generation, of our civilization on this planet.”
Senator Edward J. Markey of Massachusetts (“the single most energy efficient states,” he boasted) declared, “The planet is running a fever.”
“The Republicans do not have the votes to overturn the president’s clean power rules,” and added, “You can have 100 percent confidence that we have the president’s back.”
Senator Jeanne Shaheen of New Hampshire said the town of Peterborough (the inspiration for Thornton Wilder’s play “Our Town,” she said) “voted unanimously to build the biggest solar array in the state of New Hampshire.”
A vocal minority of Americans either does not believe that the planet is warming or acknowledge the warming, but does not think that human activities are causing it. But Senator Al Franken of Minnesota said that most Americans support the goals of the climate talks.
“They know what’s happening,” he said. “They know that not only do we have to do something, but by doing what we need to do — by moving to renewables, by moving to more efficiency, by moving to storage, by moving to new technologies — that we will create jobs, that we will prevent the kind of crises, refugee crises, that we are seeing around the world because of climate change.”
Mr. Franken, a former member of the “Saturday Night Live” cast, let loose in a way he does not often do in Washington: “I have a 2-and-a-half-year-old grandson,” he told the mayors. “I have a grandson on the way in January. Forty years from now, I don’t want to be telling them I was a member of the U.S. Senate, and don’t want them to ask. ‘Grandpa, Why didn’t you do anything?’ and ‘Grandpa, how come you’re still alive if you’re 104?’ ”
Mr. Cardin closed by telling reporters that Americans “overwhelmingly support COP 21” — as the climate change conference is known — “they want to make sure COP 21 succeeds, they are for global efforts to reduce greenhouse gas emissions and deal with climate change.”
The 10 Democratic senators — the others are Tom Udall of New Mexico, Chris Coons of Delaware, Sheldon Whitehouse of Rhode Island, Brian Schatz of Hawaii and Cory Booker of New Jersey — are expected to give a presentation at the conference in the Paris suburb of Le Bourget on Saturday.
None of the Republican senators are expected at the Paris talks. Senator James M. Inhofe, an Oklahoma Republican who has called global warming a hoax, showed up unexpectedly at the last major round of international climate talks in Copenhagen in 2009.