NEW DELHI, June 10 -- The margin is one day. By the count India's state broadcaster published on Wednesday morning, Narendra Modi has now served 4,399 continuous days as prime minister, while Jawaharlal Nehru, measured from the first sitting of an elected Lok Sabha in May 1952 to his death in office in May 1964, served 4,398. With that single day in hand, All India Radio declared Modi the longest serving elected prime minister in Indian history.

The word elected is doing a great deal of work.

Nehru did not become prime minister in 1952. He took the office on August 15, 1947, the day the country became free, and led it through partition, a war in Kashmir, the writing of the constitution and the first general election before the clock the...