MEXICO CITY — As Honduras counted votes on Monday in its presidential election, Salvador Nasralla, a former sportscaster representing a left-wing alliance, took an early lead over President Juan Orlando Hernández, an unexpected development that could reshuffle the country’s political forces if the trend holds.

A victory by Mr. Nasralla would be a sharp rebuke to Mr. Hernández, an authoritarian who has maneuvered to take control over most of the country’s fragile institutions.

On Monday, Mr. Nasralla began to take on the role of a president-elect, granting a radio interview to outline his policies and leading a rally of supporters in Tegucigalpa, the capital.

With results from 57 percent of the polling sites counted, Mr. Nasralla led Mr. Hernández by almost five percentage points. But the electoral tribunal offered no new results as the day wore on and its president, David Matamoros, said that more information would be released only when the tribunal received more data. “We cannot be irresponsible and give out information we do not have,” he said.