Signing the Vance-Owen plan without reference to local Serb leaders would have been political suicide for a man who is suspected by many low-level Bosnian Serb representatives as being weak, out of touch, and not be trusted with defending the Serbian interest.
Even the ultra-hardline Bosnian Serb commander, General Ratko Mladic, the besieger of Sarajevo, looks like a softy compared to the radicals who dominate the Bosnian Serb assembly - a reliable barometer of feeling among the 2 million Bosnian Serbs.
At a little-noticed two-day emergency session, at the end of last week, of the Bosnian Serb parliament in Bijeljina, in north- east Bosnia, the 60-odd delegates neatly tied Mr Karadzic's hands before the plenary session in Geneva even got started.
At the session, Radovan Brdjnanin, one of the delegates, set the tone, when he said: 'If I have to choose between the two evils of living alongside Bosnian Muslims and foreign military intervention, I choose the latter.'
The delegates ruled out any negotiated settlement that meant surrendering conquered territory, or backtracking on the idea of an independent Bosnian Serb state that would later unite with Serbia. None favoured accepting the Geneva plan - on the contrary, they all backed continued fighting. They also jeered General Mladic when he denounced the assassination at Sarajevo airport of the Bosnian deputy prime minister by a Serbian soldier.
The delegates drew up their own map of the division of Bosnia, which was completely irreconcileable with the Vance-Owen 10- province map - it would grant Bosnian Serbs almost the entire republic except for some purely Croat regions in the south-west and a few blobs in the middle.
After a meeting like that, if Mr Karadzic had accepted the Geneva plan, he would have signed his own political death warrant. But his seat would not have been empty for long. A whole gang of potential leaders are sniffing round for signs of a Karadzic 'sell out' and waiting to get his job.
There are solid reasons behind the Bosnian Serb delegates' extremism. Many are from majority Muslim towns, which would return to Muslim control under the Geneva plan. Others recognise they have no political future in a peacetime state. Very few seem to fear foreign military intervention.
What they do admit to fearing is the loss of the political and military support of Belgrade. Without that they are all dead. For that reason, the proposed visit today to Pale, seat of the Bosnian Serb government, by President Slobodan Milosevic of Serbia and President Dobrica Cosic of Yugoslavia could just possibly turn the Bosnian Serb parliament around in favour of the Geneva peace plan.
But that is only if Mr Milosevic decides to exert maximum pressure on the Bosnian Serbs. And no one knows yet whether he will.