Andy Burnham has warned Labour supporters that electing Jeremy Corbyn as leader would mean "giving up" on winning the next election.
The shadow health secretary's intervention came with the left-winger embroiled in yet another row over past comments- this time for suggesting it was a "tragedy" Osama bin Laden was killed by the United States.
Burnham said he was the only candidate capable of getting the Labour party back into power in 2020:
In a bid to appeal to Corbyn supporters, he added: "Don't give up on wanting to see big changes, but don't give up on winning either."
Hundreds of thousands of people signed up for infidelity website Ashley Madison in the last week, even after hackers leaked data about millions of its clients, the parent company Avid Life said today.
Earlier this month, hackers released Ashley Madison customer data after demanding the site be shut down. A second data dump contained thousands of emails and other company documents.
The company also hit back at reports that the site had few genuine female users, saying internal data released by hackers had been analysed incorrectly.
"Last week alone, women sent more than 2.8 million messages within our platform," Avid Life said, adding that 87,596 women had also signed up for Ashley Madison last week.
On Friday Chief Executive Officer Noel Biderman had left the company by mutual agreement.
Barack Obama is to venture into the Alaskan wilderness with British survival expert Bear Grylls to explore the impact of climate change on the environment for a television programme, it has been announced.
The special edition of Running Wild with Bear Grylls will be broadcast later this year on NBC.
Located on the northwest tip of America, Alaska is known for its icy terrain, mountains and freezing temperatures.
Grylls, who has served with the SAS and wrestled sharks and alligators, has taken a string of celebrities on one-on-one adventures to test their survival skills on the series.
So far, actresses Kate Winslet and Kate Hudson and Magic Mike star Channing Tatum have all taken part in the show.
The family of Paul Gallihawk who died while competing in the swimming leg of a triathlon have spoken of their devastation.
His girlfriend, Hayley Wright, added: "Paul and I had been together for five years and he was the most amazing and thoughtful partner. He was incredible in every way and he always put others before himself. I loved him to bits and always will."
The 34-year-old disappeared during a 750m swim at the start of the Ocean Lake Triathlon at Leybourne Lakes in Kent on Saturday morning.
The hunt for Mr Gallihawk, from Maidstone, resumed this morning and his body was later found in the lake by search teams.