The Tánaiste (/ˈtɔːnɪʃtə/ TAW-nish-tə,[3] Irish: [ˈt̪ˠaːn̪ˠəʃtʲə] ⓘ) is the second-ranking member of the government of Ireland and the holder of its second-most senior office.

[6] Under the Gaelic system of tanistry, the word tánaiste (plural tánaistí, pronounced [ˈt̪ˠaːn̪ˠəʃtʲiː], approximately /ˈtɔːnɪʃtiː/) had been used for the heir of the chief (taoiseach) or king (rí).

Aside from those duties, the title is largely honorific as the Constitution does not confer any additional powers on the office holder over and above the other members of the Government.

[9] Under Spring, Eithne Fitzgerald was "Minister of State at the Office of the Tánaiste", with responsibility for co-ordinating Labour policy in the coalition.

Varadkar is also one of three Tánaistí, with Micheál Martin and Simon Harris, to have previously held the office of Taoiseach before becoming Tánaiste.