Labour's election chief has defended the party from accusations of "gutter" politics following a controversial television campaign.
Douglas Alexander said he made "no apology" for the film, which depicts David Cameron and his Tory Cabinet colleagues as out-of-touch toffs who know nothing about the NHS and trample over the needs of disabled people because "they can't fight back".
The shadow foreign secretary insisted he stands by the party election broadcast amid questions over whether he was "ashamed" of the campaign, particularly in light of the fact the Prime Minister had a severely disabled son who had been treated extensively in the health service.
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Cameron's son Ivan, who suffered from a rare epilepsy condition accompanied by severe cerebral palsy, died in hospital aged six in 2009.
Alexander told BBC One's Sunday Politics programme: "I make no apology as a Labour Party for saying we need to be innovative in how we seek to present the kind of issues...
"It's factual. It was a policy-based critique of this Government of the Liberal Democrats' role within that Government."
Presenter Andrew Neil said: "You're claiming it's factual to portray the Cameron Cabinet as not even knowing what the NHS is. You have it agreeing to attack the disabled because 'the disabled can't fight back'. This, of a Prime Minister who had a severely disabled son and was treated throughout his short life by the NHS. You've gone into the gutter haven't you?"
Alexander replied: "It is a fact that many, many disabled people across the country, including in my constituency, have been directly affected by the bedroom tax."
Asked if he signed off the broadcast, Douglas said: "Of course I'd seen it. Of course I stand by the fact that disabled people are affected by the bedroom tax.
"I wish David Cameron and I wish (Work and Pensions Secretary) Iain Duncan Smith had apologised to the disabled people of the country and many of the poorest people in the country who are affected by the bedroom tax, and I hope we get that apology between now and the election."
He added: "I don't accept it's negative and personal to scrutinise the policies of the Government."
Alexander also defended a poster campaign launched by the party that appeared to suggest the coalition has put up VAT on food.
The campaign accuses Cameron and Deputy Prime Minister Nick Clegg of adding £450 to shopping bills by increasing the levy, and depicts them as "peas in a pod" surrounded by images of everyday goods including food, which is mostly exempt from VAT.
Alexander said the sum amounted to bills over the course of the parliament and insisted the picture was a "representative image" of a weekly shop.
Last month, Labour announced it had recruited David Axelrod, one of US President Barack Obama's top strategists, to help it prepare for a "tough" 2015 general election campaign.
Alexander said at the time that Axelrod, who will arrive in the coming days, had experience of "fighting negative campaigns" and was prepared to combat "fear and smear" attacks from the Tories.