Balls urges Labour to focus on Tories, not Lib Dems
Labour leadership contender Ed Balls has dismissed the Lib Dems as "cannon fodder", arguing that his party must focus its attacks on the Conservatives.
He urged his fellow candidates not to let the Tories, the larger party in the coalition government, "off the hook".
Another contender, Diane Abbott, has accused rival David Miliband of trying to "buy" the leadership contest.
And a poll suggests Labour's policy on the budget deficit damaged it at May's general election.
Ballots for the Labour leadership contest will start arriving at the homes of party members, socialist society members and affiliated trade unionists in just under a month's time, with the result to be announced on 25 September.
In an article in the Times, Mr Balls, the shadow education secretary, wrote that the coalition was "fundamentally a Conservative government" and that Labour must provide a "credible argument against slashing public spending".
He said: "There is no doubt that Mr Cameron wants to use his alliance with the Liberal Democrats to achieve what he failed in opposition - to detoxify the Conservative brand in the public mind.
"At its heart, this will remain a neo-liberal government of the right, but Mr Cameron will seek to present the coalition as dominating the centre ground, while caricaturing Labour as irrelevant, reactionary and retreating to the left."
In a warning to fellow leadership contenders Ed Miliband, Ms Abbott, Andy Burnham and David Miliband, Mr Balls said: "That's why all of us as leadership candidates, as we seek the votes of Labour and trade union members and the praise of left-wing think-tanks and newspapers, must beware of departing from the centre ground, by making unwise promises or losing touch with our constituents on issues such as crime."
But he also urged them no to "hanker after the approval of the right-wing press and conservative business groups".
The Lib Dems had "sold their principles for power", he said. "But while we must win back voters lost to the Lib Dems, we must not let the Tories off the hook."
He also criticised Education Secretary Michael Gove, saying: "The reason why the fiasco over school building cuts and the rushed Academies Bill is so damaging for the Government is that a senior Tory is in the frame.
"So Labour must focus its fire on the Tories, not just on the Liberal cannon fodder shielding Mr Cameron."
In an interview with the Guardian, Ms Abbott, the left-wing MP for Hackney North and Stoke Newington, accused shadow foreign secretary David Miliband of giving the "appearance that someone is buying the election" for Labour leader.
She said she had raised just £1,700, but claimed her rival had "£400,000 in cold cash" to promote his bid.
Meanwhile, a poll for the centre-left think-tank Demos suggests that many voters deserted Labour at the general election because they did not like the party's message on the future of public services.
When asked about the NHS, a third of voters Labour had retained thought the priority was to "avoid cuts" but among those it had lost the proportion was 13%.
Some 55% of the lost voters agreed that the priority for the NHS should be to "seek greater efficiency and end top-down control", compared with 31% of those retained.
Richard Darlington, head of Demos's Open Left project, said: "This poll will be a wake-up call for Labour's leadership candidates. Labour's next leader needs to support public sector cuts and embrace the 'Big Society' agenda [espoused by the coalition] if they are to be heard by the public."
The polling group YouGov questioned 45,000 people for its survey for Demos, carried out between 5 and 21 May.