Speaking from Glasgow, Scotland, where the conference is taking place, Biden said that the United States “showed up” to demonstrate climate leadership, calling the absence of fellow leaders Vladimir Putin and Xi Jinping “a big mistake.”

“[China] walked away. How do you do that and claim to be able to have any leadership now?” he said. “Same with Putin, and Russia. Literally, the tundra is burning. He has serious, serious climate problems. And he is mum on the willingness to do anything.”

But Biden’s defense of the U.S.’s return to climate leadership—after a four-year absence under the Trump administration, which withdrew the country from the Paris Agreement—comes amid a difficult struggle at home over whether his “Build Back Better” infrastructure plan can pass. That plan, which devotes more than half a trillion dollars to climate efforts alone, is in danger of falling apart as support is withheld by Sen. Joe Manchin (D-W.Va.), who said he had “never signed off” on the framework.

“I think that I’ve made it clear to Joe [Manchin] . . . that it’s going to lower inflation, raise wages, and increase competition and create 2 million jobs, etcetera,” he said. “I think we’ll get this done.”

Biden’s appearance also comes amid rising inflation, and sharp energy price rises in particular. Questioned on rising gas prices, Biden again turned to an approach he has taken for months, putting the blame squarely on major oil and gas producers—a somewhat incongruous admission at a climate change conference that has largely called for the end of fossil fuels.

“That is a consequence of, thus far, the refusal of Russia or the OPEC nations to pump more oil,” said Biden.

Division at home has cast a distinct shadow over Biden’s trip to Glasgow. While the U.S. President reminded attendees that he had returned the country to the Paris Agreement immediately upon taking office, and that he had been repeatedly told by other leaders how glad they were to have the U.S. back at the table on climate change, he has often seemed to be directing his message of climate action squarely back across the Atlantic, arguing on Tuesday in his national statement that his plan was a chance to make a “generational investment” in the U.S.

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