Opposition to have a say in when Dáil by-elections held

Taoiseach Leo Varadkar's power to call four Dáil by-elections is likely to be taken from him, under rules which allow the Opposition have a say.
Following the election of Fine Gael's Frances Fitzgerald, Fianna Fáil's Billy Kelleher and Independents4Change's Clare Daly and Mick Wallace to the European Parliament, their Dáil seats have to be filled.