Russell was considered a possible Liberal leader in 1912 when Joseph Ward resigned, and served in the cabinet of Thomas Mackenzie. He later served in the wartime National cabinet, holding the portfolios of Internal Affairs, Public Health and Hospitals, as well as a number of lesser responsibilities. As Minister of Public Health, he was responsible for the decision to allow to dock in Auckland in October 1918, and was blamed for the resulting Spanish flu epidemic which killed at least 8,000 New Zealanders. As a result, he lost his electorate in the 1919 election. He unsuccessfully contested the 1921 by-election for Auckland East, and Avon again in the 1922 general election, but was never again elected to Parliament.