 Weaver's efforts to merge the Democratic Party with the Liberal Democratic Party were deadlocked over questions of party organisation and by acrimony between himself and the Party leader, Ernest K White. However, in December 1944 both parties merged to become the New South Wales branch of the newly formed Liberal Party of Australia formed by Robert Menzies. Weaver was elected as the first Leader of the New South Wales Liberal Party on 20 April 1945. His term as leader of the newly formed party was to prove short-lived, however. After suffering a mild heart attack in the Legislative Assembly chamber on the evening of 7 November 1945, he drove himself home and died a week later on 12 November 1945 at Hornsby Hospital, survived by his wife, son and three daughters. At the resulting by-election on 15 December, Neutral Bay was retained by the Liberal Party candidate, Ivan Black, against a single Independent candidate with 56 %.
