Comments by leaders suggest Islamist movement may drop position of "positive neutrality" in runoff between Marzouki and Essebsi.
Tunisians are gearing up for presidential elections that look like being primarily a contest between the sitting president, Moncef Marzouki, and Beji Caid Essebsi, leader of the Nida Tounes party that won parliamentary elections.
Opposition groups debate a unified approach to the presidential election.
As tense elections approach, the country's leading parties make a show of political unity over personal ambition.
