By Paul Reynolds
World affairs correspondent BBC News website
Exposed to danger: Benazir Bhutto moments before the attack
Pakistan's major international supporters, especially the US and UK, will continue their efforts of trying to ensure that the route mapped out towards a democratic future is followed.
However, there is no doubt that the assassination of Benazir Bhutto is a severe, and potentially crippling, blow to hopes that Pakistan might emerge into a state of stability.
The risks of Pakistan imploding have once again increased.
It is a further setback for the US "war on terror", which has as part of its strategy in the region the restoration of democracy in Pakistan to offer an alternative path, away from militancy and extremism.
The strategy is very much at risk.
The government of Pakistan has blamed al-Qaeda. And the American fear is that al-Qaeda has turned its attention to Pakistan, having been frustrated in Afghanistan by the resistance put up by the Afghan government and Nato forces.
The next stage will be the elections scheduled for 8 January. These are now not being seen by diplomats as a make or break point but as something to get through in the hope that some stability can be salvaged afterwards.
Any timetable of hope for progress has been extended into an indefinite future.
Bhutto key to US plan
Benazir Bhutto was central to American hopes of broadening out Pakistan's government from the figure of General Musharraf. Washington helped engineer the political deal that saw her return and now it has seen that lead to disaster, with the loss of one of the key figures in its plan.
Now Washington is thrown back on its old ally, uncertain as to whether he can lead Pakistan to the reforms reckoned as necessary.
The British Foreign Secretary David Miliband, in his blog, pointed the way to what reforms these should be:
"[Benazir Bhutto's] assassination lays bare the responsibilities of the politicians, community and faith leaders, businesspeople and military chiefs who will now be key to Pakistan's future.
"They need to build a political system that can sustain itself, a social deal that tackles inequalities of opportunity (less than 2 per cent of national income is currently spent on education), and a structure of governance that tackles the long hangover of the days before independence (and before that) in the tribal areas.
"As for countries like Britain, with our multiple networks of politics and culture and business, we need to continue to engage to back strong systems not just strong people."
Benazir Bhutto survived an earlier attack on 18 October
Ms Bhutto's decision to carry on with campaigning despite a double suicide bomb attack on her convoy immediately after her return to Pakistan on 18 October was undoubtedly brave.
However, it underestimated the determination of those out to kill her. Moments before the attack she exposed herself to danger by waving to the crowd from her open-topped vehicle.
She herself blamed Islamic extremists for the first attack.
The ability of such militants to wreak havoc with their ruthless tactics is once again demonstrated.
Some will point to possible machinations by Pakistan's intelligence services. However, Western governments do not think these were involved, though some low-level complicity can never be ruled out in an organisation heavily infiltrated by Islamists.
Up to this point, planning for a more stable Pakistan was more or less on target.
President Pervez Musharraf had allowed both Benazir Bhutto and another former Prime Minister, Nawaz Sharif to return, had stepped down as head of the army and had been re-packaged as a civilian president.
He had set a date for parliamentary elections and had lifted the state of emergency.
The hope was that politics would be resumed and that the confrontation between the army and Islamic militants would gradually be wound down.
An end to such conflict is vital not only for the future stability of Pakistan but for the future of Afghanistan. It is from Pakistan that the Taleban are said by Western governments to conduct their war against the Afghan government and its Nato supporters.