DUP MLA Tom Buchanan has spoken about how his nine-year-old son died just a month after he became ill at school.
The politician, who is standing in the West Tyrone by-election, said that although the anniversary of Nathan's death is tomorrow - the eve of polling - he would continue on the campaign trail.
"Anniversaries are poignant days but really it's the small things on any random day of the week which bring the memories flooding back and cause the most pain," Mr Buchanan (54) said.
"You see another wee boy his age running about on a lovely spring evening, or playing with his friends, and it hits you."
The 16th anniversary of Nathan's death is tomorrow, with the polls set to open just hours later.
"No challenge I've faced or could face in life or politics, could even begin to compare with the challenge of dealing with my son's loss," Mr Buchanan said.
"I can recall every detail of what happened on May 2, 2002. It is hard holding your dying child when you remember the joy of holding him as a newborn when he first came into the world.
"To then lay a boy so young into the earth, and to learn to live with the loss, is very tough. But myself and my wife Linda have a strong Christian faith and that has given us the strength and grace to go on."
The MLA recalled that there had been no advance warning of how unwell his son had been.
"Nathan was sick in class just before the Easter holidays and the school called us to bring him home," Mr Buchanan said.
"But we didn't think that much of it. He was such a healthy wee boy. I don't remember him even having a cold.
"As the week went on, he just didn't seem to be himself.
"And then a few days later he was a bit sick again and we brought him to the hospital.
"Nothing showed up in the tests carried out. Eventually, they did a brain scan and it revealed a 3cm tumour. We were told that in the vast majority of cases tumours are benign."
Nathan underwent surgery in the RVH but the tumour was so hard the doctor couldn't remove it all.
"The analysis of the bit they managed to take away showed it was cancerous," Mr Buchanan said.
"The nursing staff were tremendous and made Nathan as comfortable as possible in the days he had left. I believe he knew how ill he was. A nine-year-old knows more than you think.
"The time was so short from his diagnosis to when we buried him, but it was very precious."
Mr Buchanan said the family had kept all of Nathan's toys.
"We would never part with any of them. They are special to us because they were special to him," he said. "We go to his grave and lay flowers a lot. Linda and I always try to look on the positive side of life.
"We know everything possible was done medically to save him. Had he been knocked down on the road in front of us that would have been different. We'd be looking back, constantly replaying it all and thinking, 'What if'?"
Mr Buchanan said the loss of a child caused some people to question their faith. "I never did. That's the nature of life - we are not here to stay," he said.
Thursday's by-election follows the resignation of Sinn Fein MP Barry McElduff, who was heavily criticised after posting a video of himself with a Kingsmill loaf on his head on the anniversary of the 1976 massacre of 10 Protestant workmen.
Sinn Fein has held the seat for 17 years and is odds-on favourite to retain it.