SAN SALVADOR (Reuters) - A preliminary count of Sunday’s midterm elections in El Salvador showed that President Nayib Bukele’s party and its allies are likely to win a congressional supermajority, which would further boost the popular leader’s grip on the Central American nation. With 80% of the vote counted on Monday morning, the electoral authority’s tally forecasts that candidates from Bukele’s New Ideas party plus the allied GANA party will win 56 seats of the 84-member unicameral Congress. Such a supermajority would allow the president free rein to pick new supreme court judges and the country’s attorney general, along with the power to enact constitutional changes, without any need to negotiate with opposition legislators. The 39-year-old Bukele, one of Latin America’s youngest presidents, won a landslide victory in 2019 on a pledge to root out corruption. Despite tensions with the previous Congress, he has maintained sky-high approval ratings ever since. Slightly more than half of the 5.3 million eligible to cast ballots participated in the election to pick lawmakers and local officials. Some election-watchers expressed concern that the lopsided results could undermine the country’s institutions. “It creates a democratic worry that we’ll lose a balance of powers,” political analyst Oscar Picardo told local television station TCS. The final vote count is expected to begin by late Tuesday.