Negotiators are gathering in South Korea in what’s billed as a final push to address the global crisis of plastic pollution.

Many nations hope to reduce the half a billion tons of plastic made each year. But pushback from plastic and oil producers, and Donald Trump’s election, could scuttle an agreement.

The fifth and final round of negotiations to create a global treaty to end plastic pollution began on Monday in South Korea. The meeting, which is taking place in Busan from Nov. 25 to Dec. 1, began with with officials urging participants to come up with and agree on a strong treaty to end plastic pollution.