United States President Barack Obama led tributes for the climate change agreement reached in Paris, hailing the pact as a potential "turning point" for the world.
However, the radio silence thus far from all 13 Republican presidential candidates highlights the deep political divide on the matter.
Last Saturday, Mr Obama praised US leadership on the issue.
"Today, the American people can be proud - because this historic agreement is a tribute to American leadership. Over the past seven years, we've transformed the United States into the global leader in fighting climate change," he said.
But he also acknowledged that the agreement did not mean the problem had been solved.
"Even if all the initial targets set in Paris are met, we'll only be part of the way there when it comes to reducing carbon from the atmosphere... But make no mistake, the Paris agreement establishes the enduring framework the world needs to solve the climate crisis. It creates the mechanism, the architecture, for us to continually tackle this problem in an effective way."
His remarks were echoed by US Secretary of State John Kerry, Democratic congressional leaders and current 2016 presidential election Democratic front runner Hillary Clinton.
"We cannot afford to be slowed by the climate sceptics or deterred by the defeatists who doubt America's ability to meet this challenge," Mrs Clinton said.
Meanwhile, her challenger, Vermont Senator Bernie Sanders, said that while the agreement was a step forward, it did not go far enough. "We need bold action in the very near future and this does not provide that," he said.
Among experts in Washington, the agreement was similarly greeted with qualified optimism, with many citing the 2009 Copenhagen Accord as reason for caution. That agreement appeared to dissolve the moment the summit ended, with negotiators disavowing various elements of it.
In a sign of how difficult a task Mr Obama will have pushing an environmental agenda forward, the Republicans largely kept mum on the deal last Saturday, continuing a policy of saying little about the ongoing climate change talks.
Only one notable figure from the conservative party said anything about the deal. Senator Jim Inhofe, a known sceptic of the human role in climate change, stressed that the US is "not legally bound to any agreement setting emission targets or any financial commitment to it without approval of Congress".
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