Tipperary TD Alan Kelly has announced his intention to stand as a candidate for the Labour Party leadership.
Mr Kelly, who has been a TD since 2011, is the first person to officially declare a leadership bid.
He will make a formal announcement at an event in Dublin tomorrow.
The race to become the next party leader got under way at the weekend.
It comes after Brendan Howlin confirmed last week that he would be stepping down from the role.
The party lost a seat in the general election, meaning they will return to the Dáil with only six seats.
The process to elect a new leader is expected to last for around six weeks.
Other possible contenders include Dublin Bay North TD Aodhán Ó Ríordáin and Louth TD Ged Nash,
Cork East TD Sean Sherlock has said he will not contest the race.
The new leader will be decided by a majority vote of the party membership.
Mr Howlin was appointed as leader in 2016, after the former Tánaiste Joan Burton resigned from the role after the election that year.