Sir Donald Irvine was forced to step down as president of the General Medical Council (GMC) after senior colleagues warned growing opposition to his leadership would soon make his position untenable, SocietyGuardian.co.uk can reveal.

In a press conference on Thursday, the day after his resignation, Sir Donald said he had decided to go 10 months early simply because he had taken his reforms of the doctors regulatory body as far as he could.

His resignation came as the GMC agreed to ask the government for legislation to put in place its reform of doctors' regulation known as revalidation - a five-yearly test of their fitness to practice.

However, he is understood to have told colleagues just last weekend that he was determined to stay on after learning that council member Dr Ed Borman was sounding out support for a vote of no confidence against him.

Senior members advised him to "seriously consider his position", warning that a vote would give the government carte blanche to impose its own regulation of the medical profession, and risked deepening the divisions between the council and doctors' leaders that have dogged his term in office.

GMC member Dr Krishna Korlipara said: "If he had decided to stay out his term of office these divisions would have got deeper and the pressure on him would have mounted. His position would have become untenable."

Professor Graeme Catto, vice-principal and dean of King's College Medical School in London, has so far emerged as the frontrunner to succeed the presidency. Other names put forward by GMC members include Sir Cyril Chandler, chair of the council's standards committee, Dr Brian Keighley, Dr Steven Brearley, chairman of the registration committee, and Dr Douglas Gentlemen, who has been involved in revalidation.

Sir Donald's tenure has been dogged with controversy. The GMC came under great pressure to reform in the wake of the Bristol and Alder Hey organs scandals. After the Shipman murders, health secretary Alan Milburn warned the council he wanted tough self-regulation or he would impose it.

Sir Donald survived an unprecedented leadership challenge in May 1999 by prominent obstetrician and GMC member Professor Wendy Savage, who led criticism that he had too readily bowed to the government in pushing ahead with his reforms - the first time that anyone had opposed an incumbent president.

The British Medical Association (BMA) also passed a vote of no confidence in the GMC last year by a majority of four to one - a move that was seen by some in the council as a personal attack on the president's autocratic style.

"There was a feeling that Sir Donald was leading a crusade without ensuring others were with him," said Dr Korlipara. "He is immensely capable but has not been a good communicator or understood the value of consensus.

"If he had decided to stay the divisions between the council, the BMA and the royal colleges that have dogged the medical profession throughout his tenure would have widened, and revalidation and governance of the GMC would have become the battleground for their disputes. His resignation provides the opportunity for someone to come in to heal these divisions."

The day after Sir Donald's resignation, the BMA threw its weight behind revalidation only weeks after its chairman Dr Ian Bogle wrote to him expressing concern about the plans, as they contained no provision for locums, retired doctors and doctors on career breaks.

"Revalidation was the final punch that knocked confidence in the GMC leadership, said Dr Korlipara. "The real anxiety for the profession was that the process would be a huge bureaucratic nightmare to the detriment of patient care, but pilots have shown it is simple and not time consuming."

Dr Borman said: "I respect Sir Donald's ability to implement change but I personally disagree with the direction taken under his leadership. To openly pursue a legislative framework for revalidation with the government when we only have a framework for consultants is unwise and inappropriate."

Fellow GMC member Dr Michael Wilson said: "Hopefully, by the time Sir Donald does go we will have addressed these outstanding difficulties. He has done a first-class job but stepping down was a sensible thing to do in the interest of the GMC."

Sir Donald was unavailable for comment.