The Liberal Democrats will have a new leader before Parliament breaks up for summer, the party has confirmed.
Despite reeling from devastating elections, the party said it had added 5,000 new members since Thursday’s bloodbath.
Just eight Liberal Democrat MPs survived, including outgoing leader Nick Clegg, and the race is expected to be dominated by Tim Farron and Norman Lamb in a battle for the party’s future.
Nominations open on Wednesday.
To get on the ballot a contender must secure the endorsement of 10% of MPs, now less than one person, as well as 200 members from at least 20 local Liberal Democrat parties.
The wider membership then elects the winner via an alternative vote system, with the verdict due on July 16.
Liberal Democrat president Baroness Sal Brinton told Sky News: “We’ve had a tradition of fighting back from pretty difficult positions and we already have the evidence for it.
“In the last 48 hours since the polls closed over 5,000 people have joined the party and the numbers are going up as we speak and that means our total membership is now up to 50,000 and rising.
“So not even just members of the public are saying we want a Liberal voice in Britain and they are doing it in a very motivated way, coming straight on to the website and joining.”
She added: “We know we have some major elections to fight next year, the Scottish Parliament, the Welsh assembly, the London assembly as well as a very large number of council seats.
“We don’t have to wait, we’re out there campaigning now.”
Former Liberal Democrat party president Tim Farron has said he will decide “in the next few days” whether to throw his hat in the ring to succeed Nick Clegg.
Mr Farron, seen as the front-runner to become the new leader, said he was determined to play a “big role” in rebuilding the party after its disastrous showing in the general election.
“I am listening to members and activists, our other parliamentarians in Westminster, the European Parliament, Scotland and Wales, and hearing their views,” he told Sky News.
“My job surely is to respond to that and I will do so in the next few days.
“I am ruling nothing in and nothing out.
“Our party absolutely must survive and thrive and I am determined to play a big role in making sure that happens.
“What role that is is up to the members.”
Mr Clegg dramatically quit as Lib Dem leader after the party was left with a rump of just eight MPs following its election night bloodbath.
Mr Farron, who is on the left of the party, said: “What we need is a Britain which draws together with strong liberal values.”
Other potential leadership contenders from the remaining group of Lib Dem MPs are thought to include Norman Lamb who was health minister in the coalition and Alistair Carmichael who was the Scottish secretary.