Brazilians cast ballots Sunday in a presidential runoff that pits leftist incumbent Luiz Inácio Lula da Silva against right-wing Senator Flávio Bolsonaro, the eldest son of former President Jair Bolsonaro.

The contest follows a first-round vote on October 4 in which Flávio Bolsonaro secured 47.03 percent of valid votes to Lula's 45.16 percent, advancing both to the runoff without a majority. Polls have shown the race narrowing to a statistical tie in the final days, with most surveys placing Flávio Bolsonaro at or slightly above 50 percent of valid votes.

Recent polling averages compiled by multiple outlets put Flávio Bolsonaro around 51 percent to Lula's 49 percent. Prediction markets have favored the conservative candidate throughout the runoff period. A win for Flávio Bolsonaro would extend a regional shift toward right-leaning governments in Latin America and align Brazil more closely with U.S. policy priorities under the current administration.

Lula, seeking a fourth term, has campaigned on his record of social programs and international diplomacy. Flávio Bolsonaro has emphasized economic reforms, security, and closer ties with conservative allies abroad. Markets reacted positively to the first-round results, with Brazilian assets rising on expectations of pro-business policies.

Voting occurs across the country with polls scheduled to close at 5 p.m. local time in Brasília, though some extensions were reported in certain areas due to transit and logistical issues. First results are expected shortly after polls close, with the electoral authority releasing tallies progressively.

The outcome will determine leadership of Latin America's largest economy for the next four years and influence the direction of regional politics. Historical precedent shows no second-round comeback for a first-round runner-up in Brazil's modern democratic era, though late shifts in turnout remain possible.