The leadership of the Progressive Democrats is to be decided in a postal ballot that is expected to take place at the end of April.
Senators Ciarán Cannon and Fiona O'Malley both declared their intention at the weekend to contest the position.
This followed a decision by the party's general council, meeting on Saturday, to change the rules of the contest. Previously, the race was confined to TDs, but now Senators, councillors and others who have been members of the party in good standing for at least two years are also eligible.
Acting leader and Minister for Health and Children Mary Harney welcomed the move, stressing that it was "important that a new generation takes up the leadership of the party at this time".
Detailed arrangements regarding the election - the date for the close of nominations and the timing of the postal ballot - will be made at a meeting of the national executive, probably on Thursday.
A total of 3,900 members are eligible to vote. The signatures of 20 party members are required for a nomination.
Tributes were paid at the meeting to party general secretary John Higgins, who announced he was moving on after 10 years. He is taking up a new position as chief executive of the Retirement Planning Council of Ireland but said he intends to remain a party member.
The council meeting, which was held at a Clondalkin hotel, was attended by more than 150 members including former leader Des O'Malley, former minister of state Tim O'Malley, former senator Tom Morrissey and other prominent party figures such as Paul MacKay and Brendan Malone. Senators Cannon and O'Malley both addressed the meeting and spoke of their vision for the future of the party.
Senator Cannon took the opportunity formally to announce his candidacy and, speaking to the news media afterwards, Senator O'Malley also declared her intention to run.
Speaking yesterday, Senator O'Malley said: "Politics is in my blood and, in that sense, I always expected that, one day, I would seek the leadership of the party.
"I didn't quite expect that it would come this soon. In an ideal world, one would have a lot more experience, but I am happy to bring the depth of experience that I have to date, having been a TD for five years, to the party.
"Over the lifetime of the governments that the Progressive Democrats have been part of, we have demonstrated that full employment offers the best opportunities for people to provide for themselves and this has been a key element in delivering social justice."
She said she would be issuing a "vision document" shortly.
Paying tribute to the outgoing general secretary, party chairman Peter Wyer said: "We owe John a deep debt of gratitude. For 10 years he worked tirelessly in the best interests of our organisation, we wish him every success in his new role."
