The battle for North Belfast has turned nasty after the DUP accused Sinn Fein of penning a fake letter to smear its candidate.
A letter purporting to be from the mother of a disabled child was posted to hundreds of homes in unionist areas of the constituency yesterday morning.
It claims DUP candidate Nigel Dodds refused to meet the parents of a boy with cerebral palsy. The letter also criticises the DUP stance on the Welfare Reform Act, which Sinn Fein has opposed.
The claims are particularly painful as Mr Dodds had a son, Andrew, with spina bifida, who he and his wife Diane doted on and cared for around the clock.
Andrew died when he was just eight years old.
Mrs Dodds, an MEP, headed up the first ever official World Spina Bifida and Hydrocephalus Day promoted by the European Union.
Mr Dodds says he believes the letter is "entirely fake", and originated from Sinn Fein.
A spokesman for Sinn Fein denied responsibility for the letter.
In a statement Mr Dodds said: "From first thing our offices in north Belfast were contacted by dozens of residents in mainly unionist areas wishing to alert us to an anonymous letter they received, by first class post, containing a false story.
"It is firmly our belief that this is an entirely fake letter originating from Sinn Fein as a desperate dirty trick in the mouth of the election. I am glad to say that many have responded by confirming that this attempted deception has reinforced their intention to vote for myself on Thursday.
"This ploy, which we believe originated from Sinn Fein in an attempt to cause unionists not to vote, has backfired dramatically and will instead only increase their determination to vote for myself."
A Sinn Fein spokesman said: "Sinn Fein are not responsible for this letter. We do not believe in negative campaigning.
"What is clearly apparent, though, is that Sinn Fein are not the only people opposed to the DUP's support for austerity or further savage Tory cuts."