Ecuadorian President Daniel Noboa's plan to revitalise the country's largest oil field appears to be unravelling amid his challenging re-election campaign ahead of the April 13 runoff vote.

The controversial deal to transfer operations of the Sacha oil field from Ecuador's national oil company Petroecuador to a consortium led by China's Sinopec and Canada's Petrolia has drawn fierce criticism.

Oil workers' unions and legislators from the leftist Citizens' Revolution party, which holds a majority in parliament, denounced the deal as unconstitutional, claiming it would cost the government $8bn.

The arrangement, structured as a production-sharing contract, aims to boost output from the current 74,600 barrels per day (bpd) to 100,000 bpd by 2028, with the consortium pledging $1.7bn in investment over six years.

Left-wing candidate Luisa Gonzalez has promised to cancel the arrangement if elected. “We are going to overturn this concession. We will revoke it because we will not hand over Ecuadorians' resources! This contract was made outside the law,” Gonzalez publicly announced, raising constitutional concerns about potential international arbitration clauses in the agreement.

Noboa has since issued an ultimatum demanding Sinopetrol pay the $1.5bn entry bonus by March 11, approximately one month earlier than initially agreed. Analysts speculated that this accelerated deadline is designed to fail, allowing the president to extricate himself from the politically damaging deal after narrowly defeating Gonzalez by just 15,000 votes in the first electoral round.

The political manoeuvring unfolds as Ecuador struggles to boost oil production in its mature fields. The election outcome will significantly impact the future of Ecuador's oil sector, with the two candidates holding diametrically opposed views on foreign investment and resource development.

For conservative Noboa, navigating this controversy while maintaining his economic vision has become a critical challenge in his bid to secure a full presidential term, especially given the close margin by which he won the initial electoral round. As for Gonzalez, a protégé of exiled former president Rafael Correa, reversing the incumbent president’s oil agenda has become a priority, especially when it comes to revoking the transfer of operations in the Sacha oil field. Depending on who wins the April 13 run-off, Ecuador’s vital oil industry could be heading down either one of two vastly different routes.