He has told friends he wants to "see things through" despite warnings from his doctor to cut down on his workload - most effectively by standing down in his Foyle constituency at the forthcoming General Election.
Hume, who will be 60 this month, is suffering from over work and hypertension. He is dismayed and angered by the slow unravelling of his initiative to take the gun out of Irish politics, but insists it is "not depression".
He could be forgiven for being depressed. Last week as he rested in his country retreat by the side of Lough Foyle, in Greencastle, Co. Donegal, he was approached by RTE, the Irish state broadcasting system, for a New Year interview.
The SDLP leader readily agreed and made an impassioned appeal to the Republican men of violence to listen to what the Irish people are saying. "I am asking the IRA straightforwardly to lay down their arms and join the rest of us in building a new society," he said.
So far, so good. It was the standard Hume line. He has long argued that only when the IRA has unequivocally restored the ceasefire could Sinn Fein enter all party talks crucial to the future of Northern Ireland. Then, as the interview closed, he was asked if he could confirm his candidacy for the Westminster elections. Hume replied testily: "No". He added: "I am of course heavily burdened with the work that I have in terms of the European Parliament, the British Parliament, the leadership of my party, and of course the local work one has to do in politics."
Aha! This was enough to set the "Europa Fusiliers" - Belfast correspondents of broadsheet London newspapers - running for the telephones. Obviously, there was a plot. Hume was not only quitting Westminster but positioning himself for the presidential election in the Irish Republic in November, should Mary Robinson decide against seeking a second term.
It was a dazzling superstructure to erect on the single word "no", and none of the correspondents contacted Hume to ask if that was his real intention - presumably because the answer to that question would also have been "no".
Relaxing over a glass of white wine on Thursday night Hume flicked through the Teletext versions of his RTE interview. They concentrated entirely on his peace plea. But then the phone rang. It was a friendly BBC journalist, tipping him off that Newsnight had just previewed the next day's papers. His exotic presidential ambitions featured prominently on the front pages of the Times, the Guardian and the Daily Telegraph in varying tones of confidence.
Hume was by turns bewildered, irritated and annoyed. Talk of bidding for the Irish presidency was "total crap". And he had not made up his mind whether to defend the Westminster seat he has held since 1983. Terse calls to the newspapers followed. The following day Hume issued a statement from SDLP headquarters in Belfast describing the speculation as "the product of silly season journalism".
Which, in a way, it was. But it also refocused the spotlight on the faltering peace process and John Hume's place in it. To many people in Northern Ireland, and elsewhere, he is the peace process and it would be unthinkable without him. It was his courage in engaging Gerry Adams, the Sinn Fein president, in dialogue that produced the August 1994 ceasefire and laid the basis for the London-Dublin Framework Agreement that remains the best prospect for a political settlement in the province.
Hume is still only human, however. He has fought the good fight since the Troubles restarted in his native Derry on 5 October, 1968, preaching non violence and accommodation between the Protestant Unions and Catholic Nationalists. Initially he was enthusiastic about Westminster, but over the years he has wearied of the time-consuming adversarial contest in the Commons, preferring to influence events through his contacts in Dublin, the United States and Europe. He has indeed discreetly canvassed the possibility of quitting Westminster and leading the SDLP from the European Parliament in Strasbourg, where he has long been an MEP, but his colleagues doubt that his own unique role in the peace process could be conducted at such long range.
A highly placed party source added: "The wider political family in the SDLP would feel it was an inappropriate time for him to give up Westminster now." They concede reluctantly, that any change in Northern Ireland's constitutional position can only be made on the floor of the Commons. Dr Joe Hendron, SDLP MP for West Belfast who is almost certain to lose his seat to Sinn Fein, yesterday publicly called on him to stay.
The dangers of Hume's departure are all too clear. Mitchel McLaughlin, chairman of Sinn Fein, will say in a Republican address in Limerick today: "So long as Gerry Adams and John Hume continue their collective enterprise, then we have grounds for hope and reasons to weigh in behind their endeavours."
Sinn Fein clearly rely on Hume as their guarantee of access to Dublin and the US government. Without him, they recognise, the peace process as it is now structured would inevitably collapse. The Unionists take a similarly realistic, if not cynical, view. Hume must stand again, argues the Ulster Unionist leader David Trimble, to avoid Sinn Fein taking his seat.
This is almost certainly overblown rhetoric. Derry is a much more prosperous, middle- class city today than it was before the advent of the Hume era. Information technology firms, particularly from the US, have moved in to replace industries like shirt making, and tourists are returning.
But staying on will not diminish the pressure. In the Irish Independent yesterday, Hume's most articulate enemy, the veteran politician and journalist Conor Cruise O'Brien, excoriated the Anglo-Irish division of Dublin's Department of Foreign Affairs for being "made up exclusively of admirers of John Hume". He sneered that the Hume/Adams process - "what there's left of it" - is dominated by the Sinn Fein president.
The Unionists have called for talks to be put on ice until after the election, and influential backbench Tories are privately telling John Major that the peace process is finished.
It will require a broad back to live with daily doses of this treatment and Hume has taken one bit of medical advice: he is walking for half an hour every day. His political colleagues are growing confident that he will not walk away from the great challenge he set himself nearly 30 years ago.Reuse content