Tanaiste
Information
The Constitution states that the Taoiseach must nominate a member of Dáil Eireann for the position of Tanaiste. The Tanaiste is the deputy Taoiseach.
They act in place of the Taoiseach if the Taoiseach is abroad or ill. If the Taoiseach were to die or become permanently incapacitated, the Tanaiste would stand in until a new Taoiseach was appointed.
The Tanaiste may also hold a ministerial portfolio, which means that they may also be a minister of a Department of State. Information on the current Tanaiste is available here.