Senator Barkley died in office on April 30, 1956. Republican leaders encouraged Cooper to return from India and seek the seat, but Cooper was reluctant to give up his ambassadorship. After a personal appeal from President Eisenhower, however, Cooper acquiesced and declared his candidacy in July 1956. Even after leaving India, he maintained close ties with the country's leaders and was the official U.S. representative at the funerals of Prime Minister Nehru in 1964, Prime Minister Lal Bahadur Shastri in 1966, and Prime Minister Indira Gandhi in 1984.