YANGON, Myanmar — Framed photographs of Daw Aung San Suu Kyi, the Nobel laureate, cover the walls of his small living room, but U Myo Khin, a longtime democracy activist, has harsh words for the woman he idolized for years as a crusader against dictatorship.

“The goal is still democracy, but her behavior is authoritarian,” said Mr. Myo Khin, whose credentials in the democracy movement include 12 years as a political prisoner. “She is losing people like us who have been strong supporters for a very long time.”

It was taboo for many years among democracy activists in Myanmar to speak ill of Ms. Aung San Suu Kyi, who became a global icon of democracy and a symbol of resistance against oppression when Myanmar was ruled by a brutal military junta. Any criticism of The Lady, as she is known here, was seen as strengthening the hand of the generals.

But as landmark elections approach — a contest described by some as a once-in-a-generation opportunity for democratic forces — Ms. Aung San Suu Kyi is being openly criticized by activists, commentators and intellectuals. They accuse her of a my-way-or-the-highway approach to managing her party. They question her decision to ally herself with a now-marginalized former general. And they say she is missing an opportunity to build a grand coalition of democratic forces, including minority ethnic groups whose support may be crucial after the election.