The accidental diplomat in Kabul

If John Kerry had not gone to Kabul, it is possible that the Afghan picture would look very different. The Senator for Massachusetts huddled with Barack Obama back in Washington yesterday, telling reporters later that a decision on troop numbers before the election results were clear would lack "common sense". It seem likely that his views will be taken seriously by Obama: details of the role he played in persuading President Hamid Karzai to accept a run-off vote began to emerge yesterday, and suggested that his influence was critical in the Americans getting the result they wanted.

Karzai had been subjected to telephone calls from world leaders, UN entreaties, and pressure from the international body charged with validating the results; in the end, though, the decisive factor for Mr Karzai was a quiet walk in the palace gardens with Mr Kerry, accompanied by reminiscences of the travails of losing an election to George Bush.

Obama was full of praise for his emissary yesterday, thanking him for his "tireless" work. Yet as smooth as the results seemed in retrospect, Mr Kerry's mission was an accidental one. It was secretary of state Hillary Clinton who connected the dots last week between a long-planned trip by Kerry to the region and the possibility of a crisis if President Karzai resisted calls for a run-off. She sent an official to brief him on what he might do before he left.

On Friday night, Kerry was eating dinner with troops in Kabul when the US ambassador, Karl Eikenberry, told him that Mr Karzai was indeed showing signs of balking at the findings of the voting commission. It was agreed the two would pay a surprise visit to Karzai's palace that night.

Thus Kerry – accidently referred to as "Secretary Kerry" by White House spokesman Robert Gibbs yesterday – found himself at the start of almost 20 hours of on-off negotiations with President Karzai over four days. Mr Karzai also received calls from Prime Minister Gordon Brown, French Foreign Minister Bernard Kouchner and the US Secretary of State, Hillary Clinton, all of whom urged him by telephone to accept the findings of fraud. But Kerry was the spearhead. Eventually – after the two men had consumed "gallons of tea" and pounds of lamb – Karzai agreed to accept the findings in a press conference at noon on Tuesday.

The deal seemed settled, only for Mr Karzai to get cold feet at the last moment. It was then, according to sources quoted by Associated Press, that Mr Kerry took the President on a long walk through the palace gardens. He told Mr Karzai of his own decision to concede to President George Bush after the 2004 US election even though he had doubts about ballot-counting in Ohio. There are times, he said, when tough decisions have to be taken putting country before self. The delayed press conference followed.

The good news for Mr Karzai is that a new vote would return a little of the credibility that he has lost. Moreover, the US and Nato would have a partner in Afghanistan they know, even if the lustre that Mr Karzai once had has long since worn off.

But if a run-off can be held successfully the list of things Washington will be expecting of a new Karzai government will be long. First on that list will be a new push to persuade the president to make a serious effort to root out corruption in the government. So far he has shown little appetite for the exercise. To persuade him otherwise, another gargantuan diplomatic effort may be necessary. How that will be executed if Mr Kerry is back in the Senate remains to be seen.