What is the relationship and political history between Kizza Besigye and President Yoweri Museveni?

Kizza Besigye and Yoweri Museveni share a complex history that evolved from close collaboration to political rivalry. Initially, Besigye served as Museveni's personal doctor during the 1980s bush war, but the two men later fell out over political differences. Besigye emerged as a leading opponent to Museveni, who has held power for nearly 40 years. He has challenged Museveni in four presidential elections, losing each time but consistently rejecting the results due to alleged irregularities that authorities have denied. Their rivalry represents one of Uganda's most significant political conflicts, with Besigye facing numerous challenges in his opposition role.