Leader of the Government in the Senate (Australia)
The current Leader of the Government in the Senate is Mathias Cormann. The current Deputy Leader of the Government in the Senate is Simon Birmingham, who was appointed on the same date following the resignation of Mitch Fifield.
2018 National Party of Australia leadership election
Under the Coalition agreement between the Liberal and National Parties, the Nationals' leader serves as deputy prime minister in a Coalition government. Therefore, the decision of National Party members would determine who succeeded Joyce as deputy PM. Following the 2016 election, sixteen National Party MPs sat in the Australian House of Representatives (including six from the Queensland Liberal National Party, and Joyce himself as a backbencher since his announcement). Some of the highest-profile National Party parliamentarians, namely deputy leader Bridget McKenzie and Resources Minister Matt Canavan, sit in the Senate; no senator has served as deputy prime minister in the history of the position.