As record numbers of fires scorched the Amazon rainforest during each of the past two summers, far-right Brazilian President Jair Bolsonaro knew where to turn for refuge from international scorn: the United States. President Donald Trump is an ideological ally and one of the few world leaders whose climate skepticism matches Bolsonaros own .

At the first presidential debate in early October, however, Democratic nominee Joe Biden made clear that if he were to defeat Trump in Novembers election, the U.S. government would no longer sympathize with climate change denial. Biden said he would create a $20 billion international fund to incentivize Brazil to stop tearing down the Amazon. If Bolsonaro rejected the plan, Biden said, Brazil would face economic consequences.

The proposal wasnt new, but this time it drew Bolsonaros ire. Brazil does not accept bribes, he said in a statement posted to Twitter and Facebook . Bidens statement, Bolsonaro said, was a clear sign of contempt for cordial and fruitful coexistence between two sovereign nations.

For months, Biden has insisted that climate change will feature prominently in his agenda at home and abroad. Choosing Brazil as his go-to example of Trumps failure on the world stage was perhaps the clearest indication yet that he intends to follow through on that pledge.

And should he win, Biden is unlikely to back down in the face of Bolsonaros anger. Few countries are more important to the fight for planetary survival than Brazil: Preservation of the Amazon rainforest is one of the simplest ways to reduce carbon emissions and limit the rise of global temperatures. From 2004 to 2014, for instance, Brazils successful efforts to limit deforestation in the Amazon were almost solely responsible for global emissions reductions. Without Brazil on board, Bidens efforts to make international progress on climate wont accomplish much even if he makes the U.S. as bold and forward-thinking as it should have been long ago. His climate agenda depends not only on his own ambition but on his ability to alter Brazil and Bolsonaros too.

In any relationship that Joe Biden has with leaders around the world, climate change will be at the top of that agenda, and that includes Brazil, said Juan Gonzalez, a longtime Latin America adviser to Biden who served as a deputy assistant secretary of state in the Obama administration. Anybody, in Brazil or elsewhere, who thinks they can advance an ambitious relationship with the United States while ignoring important issues like climate change, democracy, and human rights clearly hasnt been listening to Joe Biden on the campaign trail.

Risking Pariah Status

Thanks in large part to the countries shared economic interests, the U.S.-Brazil relationship has remained strong, if often overlooked, even during times of deep ideological differences and occasional chills. As vice president, Biden played a central role in that relationship at one of its modern low points. Following 2015 revelations that the U.S. had spied on its South American neighbor, President Barack Obama sent Biden to repair relations with Brazils then-leader, Dilma Rousseff.