Paraguay ratified the Mercosur-European Union free trade agreement on Tuesday, finishing the South American side of the pact that aims to create one of the world’s largest free trade zones, according to the Associated Press.

The vote made Paraguay the “latest and final South American country to ratify” the deal, the AP reported from Santiago, Chile. The European Commission said it would provisionally ratify the agreement, meaning it could start operating even as European lawmakers’ legal challenge continues through the European Court of Justice.

The agreement was negotiated for about a quarter century among countries that, together, account for more than 700 million people and about a quarter of global gross domestic product, the AP said. In Paraguay, the Chamber of Deputies approved the treaty after the Senate gave its green light nearly two weeks earlier, and the AP said the session’s approval came from 58 deputies present unanimously.

After deputies endorsed the deal, Paraguay’s process moved to the presidential stage. The AP said the agreement now awaits President Santiago Peña’s signature, completing what it called the process of accession and validation on the South American side.

Mercosur’s other founding members had already completed their parts of the ratification process. Uruguay ratified in late February, and Argentina completed its approval the same day with a large majority in both the Senate and the Chamber of Deputies, according to AP. Brazil, Mercosur’s largest economy, ratified in early March after the Senate unanimously approved the deal following lower-house approval, the report said.

With Paraguay’s ratification, four founding members—Uruguay, Argentina, Brazil and Paraguay—have now approved the agreement. The AP said Bolivia, which joined Mercosur later, did not participate in the negotiations but would be able to join the deal in the coming years.

In Paraguay’s parliamentary session, deputies praised the agreement’s expected effects for both blocs, AP reported. Deputy Rodrigo Gamarra, from the ruling Colorado Party and current president of the Mercosur Parliament (Parlasur), said: “This is a historic agreement for Paraguay, for the region, and for the world. We are creating what is possibly the largest market in the world.” Deputy Juanma Añazco, also from the Colorado Party, said: “This provisional agreement is the bridge to full integration.” Deputy Alejandro Aguilera, from the ruling coalition, said the agreement followed “years and years of negotiations and reluctance … achieving this is truly historic,” according to AP.

The AP reported that sectors of the opposition also expressed support during the session. Independent Deputy Raúl Benítez said, “where there is isolation, we respond with multilateralism.”

Across the EU, the AP said countries’ legislative bodies do not need to ratify the major trade deal individually. But it said the European Parliament would again vote on ratifying it if and when the court case concludes that the agreement does not break EU treaties.

Opposition inside Europe included France, left-wing groups and farmers’ unions, the AP said, with critics arguing that the deal could destabilize the European agricultural sector. The AP also said the treaty comes as political fragmentation and economic shifts challenge the international landscape, and that several European nations face security challenges while tensions with the United States strain their environment.

The AP identified European Commission President Ursula von der Leyen and Brazilian President Luiz Inácio Lula da Silva as main driving forces behind the agreement. In a statement cited by AP, von der Leyen praised the pact as “one of the most significant trade agreements of the first half of this century,” and said: “Mercosur embodies the spirit with which Europe operates on the global stage. Europe is strengthening itself and gaining independence.”