The Rev Ian Paisley remained seriously ill in hospital tonight as his family maintained a vigil at his bedside.
Dr Paisley (85), now Lord Bannside, was rushed to the hospital in Dundonald, east Belfast, on Sunday with suspected heart failure.
His family was with him at the hospital's intensive care unit today. The North's former first minister was taken to the hospital, just 10 days after preaching his final sermon as a minister.
Dr Paisley is a former moderator and founding member of the Free Presbyterian Church and was MP for north Antrim for almost 40 years.
His son Ian junior, who succeeded him at Westminster, was with other family members at the hospital through the day. He left at about 4.30pm without making any public comment on his father's condition.
There had been concerns several years ago about Mr Paisley's health, when he lost weight and looked gaunt.
But he made a good recovery from heart problems and while his voice was showing signs of obvious weakness, some people who were there for his farewell sermon at the Martyrs Memorial Church in Belfast on January 27th remarked on how well he appeared for his age.
After withdrawing from church and public life he was planning to write his autobiography.
DUP Assembly members, who were told of his condition at their weekly parliamentary meeting at Stormont yesterday morning, prayed that the former DUP leader, first minister and moderator of the Free Presbyterian Church would recover.
Dr Paisley's wife, Eileen, issued a statement confirming he was undergoing treatment. A statement on her behalf said: "She requests that the family's privacy be respected at this difficult time."
The Assembly was sitting at parliament buildings, Stormont, yesterday and throughout the day Assembly members, including some Sinn Féin MLAs, inquired about Dr Paisley's condition.
Dr Paisley, after a political and church career going back more than 60 years, gave his last sermon on Friday week to a congregation of 3,000 at the Martyrs Memorial Church which he founded in south Belfast. Although frail, he was in cheerful humour and with his family joined in the celebrations on the night.
With his wife Baroness Paisley, twin sons Ian and Kyle and daughters Rhonda, Sharon and Cherith he told of how he was planning to devote some of his remaining years to completing his autobiography.
"I am exceedingly happy that I've had the privilege of being the preacher here for 65 years, and that's a long time," he said. "We have seen a miraculous work done and we have seen a great change in our city in many ways. We've seen a change spiritually by people having respect for the Bible."
Dr Paisley was taken to hospital after he became ill on Sunday. Sources initially feared he may have suffered a heart attack but later it was believed that he was suffering from general heart problems. It was learned last year that he had to have a pacemaker inserted after he became ill in the House of Lords.
Some of his DUP colleagues were last night praying he would make the same recovery as he did in 2004 when during a period of difficult political negotiations he became seriously ill. It was a time, he later admitted, when he had "walked in death's shadow".
Throughout most of his political life Dr Paisley led the DUP in opposing various attempts to achieve a powersharing settlement for Northern Ireland. In the past five years, though, after the DUP firmly established itself as the dominant unionist party, he surprised many by agreeing to share power with Sinn Féin and by holding to that agreement.
Additional reporting by PA
