BOGOTÁ, Colombia — Researchers from the Massachusetts Institute of Technology have cast doubt on a claim that Bolivian officials engaged in fraud to help Evo Morales, the longtime president, win re-election.

The researchers, while not definitively ruling out the possibility of any fraud, waded into a fierce domestic and international debate over Mr. Morales’s legitimacy. The country’s first Indigenous president, he was a historic but contentious figure, forced out in November after violent protests and accusations that his allies had rigged the election.

“The statistical evidence does not support the claim of fraud,” the researchers, John Curiel and Jack R. Williams, wrote in The Washington Post. Their work was commissioned by the Center for Economic and Policy Research, a liberal research group based in Washington.

Mr. Curiel and Mr. Williams, from M.I.T.’s Election Data and Science Lab, said they were contracted to conduct an independent analysis.