Mercosur summit overshadowed by fate of EU trade deal with Argentina's new president in the wings

On the campaign trail, Milei threatened to quit Mercosur, exploding the common market with Brazil, Uruguay and Paraguay

Incoming president Javier Milei is a radical libertarian who has said Mercosur serves no purpose. (AP Photo/Natacha Pisarenko)

Presidents of the four Mercosur nations meet for their annual summit on Thursday in Rio de Janeiro with black clouds hovering over the fate of a trade deal with the European Union, as well as the future of the South American common market itself.

They had hoped to announce a free trade agreement with the EU, opening markets home to some 732 million people.