Donald Tsang has been acting chief executive since Tung Chee-hwa resigned in March. Hong Kong law requires government officials to resign if they wish to run for chief executive.
Mr. Tsang's resignation followed the Hong Kong legislature's approval of a bill clearing the way for the July 10th vote by an 800-member committee controlled by Beijing. The bill says the winner of this election will only serve out the remainder of Mr. Tung's term, and not a new five-year term.
Mr. Tung stepped down, citing ill health.
Some information for this report provided by AP, AFP and Reuters.