text: The limestone monument, which the Labour leader suggested could be placed in the garden of Number 10, has already attracted widespread comment.
  The 8ft stone has already prompted its own hashtag #EdStone and has been mocked by David Cameron and Nick Clegg.
  But Mr Miliband said he wanted to be the first politician to "over deliver".
  The Labour leader unveiled the pledge stone at a hustings event on Sunday.
  Landscaping issue
  The ridicule of the idea was put to Mr Miliband on BBC Radio 4's Today programme.
  But he said: "Our pledges are carved in stone.
  "I think trust is a huge issue in this election - the difference with our pledges is they are not going to expire on 8 May.
  "Nick Clegg went into the last election saying he'd cut tuition fees - he trebled them. David Cameron went into the last election, saying 'no ifs no buts - net migration into the tens of thousands' - it's 298,000.
  "We're setting out promises - they don't expire on May 8. They don't disappear."
  Rock 'reminder'
  Asked whether the monument would be placed in Downing Street if he becomes prime minister, Mr Miliband said: "I'll leave the landscape gardening to other people.
  "But I'm absolutely clear about this: There are millions of people who are turned off this election... because they think no politicians keep their promises.
  "I want to be the first person in British politics for a generation to under-promise and over- deliver, not over-promise and under-deliver. And that's why I've set out these pledges, and that's why I'm serious about keeping these pledges."
  Mr Miliband said the stone was "to remind the British people, to remind working people in this country that I'm absolutely serious about changing the way this country works."
  He added: "In the next few days this is a once in a generation election for the British people about who Britain is run for. Is it run for working people? Or is it run for the richest and most powerful? That is the choice between me and David Cameron."
  'SNP chisels'
  But the introduction of a pledge stone sparked a spate of social media jokes, with photoshoppers working overtime to turn Mr Miliband into Moses and more than a few comparisons with BBC political drama The Thick of It.
  When asked what he thought of it David Cameron remarked: "If you've got a problem with judgement ... I don't think that's going to help."
  Mr Clegg also mocked the stone tablet, telling Lib Dem activists in Bermondsey, south London there was "nothing attractive about the instability of a hapless Labour minority administration, regardless of these great gravestones they are apparently going to erect".
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  Former Conservative leader William Hague said: "This is yet more evidence that Ed Miliband is simply not up to the job of being prime minister. And if he does make it to No 10, Nicola Sturgeon and the SNP will take their chisels to Miliband's vanity stone and write their own demands all over it."
  London Mayor Boris Johnson wrote in the Daily Telegraph: "What was he drinking? What was he smoking? What was he on when he came up with this one?
  "Keep taking the tablets, Ed - don't erect them in government offices."
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target: Ed Miliband has defended his decision to carve Labour promises in stone - insisting he wants to show the public his pledges will not expire on 8 May.