Why did Ali ibn Abi Talib, may Allah be pleased with him, leave Medina, the center of the Caliphate, and head to Kufa, even though it was a center of sedition and a gathering place for the killers of Uthman?

'Ali (may Allah be pleased with him) was pledged allegiance as Caliph in Medina after the killing of 'Uthman (may Allah be pleased with him). All the Companions pledged allegiance to him. Then he went to Basra to confront 'Aishah, Talhah, and Al-Zubair. After the battle, he entrusted the governorship of Basra to 'Abdullah ibn 'Abbas and departed for Kufa. 'Ali tried to reach an agreement with Mu'awiyah, but Mu'awiyah insisted on the surrender of 'Uthman's killers. Consequently, matters fell apart, Mu'awiyah gained independence over Syria, and other regions seceded from 'Ali's rule. Nothing remained for him except Kufa, which he adopted as the seat of the Caliphate.