Why did Sun Yat-sen make an agreement with Yuan Shikai in 1912?

Sun Yat-sen entered into an agreement with Yuan Shikai in 1912 primarily because he recognized that his own provisional government in Nanjing was weak.2

By that time, Yuan Shikai—a powerful imperial minister and commander of the elite Beiyang Army—had been entrusted with full power by the Qing dynasty to suppress the revolution. To facilitate the abdication of the emperor, unify the country, and ensure the transition to a republican government, Sun Yat-sen agreed to resign from the presidency in favor of Yuan. This political compromise allowed for the formal end of the 268-year-old Qing dynasty and the establishment of a unified provisional government under Yuan's leadership.123