Ms Róisín Shorthall last night became the third person to declare her candidacy for the position of Labour Party leader.
The Dublin North West TD said she wanted to "re-establish the Labour Party as a strong and distinctive force" and take the party "in a radical new direction".
Ms Shortall was critical of outgoing leader Mr Ruairi Quinn after the party's failure to make gains in the General Election.
Formerly the party's spokesperson on education and children, she was not reappointed to Labour's front bench after the election.
In a statement announcing her intention to run, Ms Shortall said: "Before the last general election, people didn't know where the Labour Party stood on key issues. We hadn't a clear message and more importantly, people didn't know our intentions on coalition."
She said party must return to "traditional Labour values of honesty and fairness" and wanted "the welfare of families" to become Labour's main political priority.
Meanwhile, The Irish Timesreports this morning that Labour's star electoral performer, Mr Willie Penrose, is to run for the position of deputy leader, forming a "dream ticket" with Mr Pat Rabbitte, who yesterday declared he would run for leader.
Labour's deputy leader, Mr Brendan Howlin, has also declared his candidacy for the leadership. Speculation still surrounds Dún Laoghaire TD Mr Eamon Gilmore's intentions.