LONDON – More than a year ago, Abu Musab al-Zarqawi, the most wanted man in Iraq, predicted that elections there would pose a mortal threat to the insurgency.

In a letter intercepted by American forces, Mr. Zarqawi tells Al Qaeda leaders that the fight would be “difficult because of the gap that will emerge between us and the people of the land.

“How can we fight their cousins and their sons and under what pretext after the Americans, who hold the reins of power from their rear bases, pull back? Democracy is coming, and there will be no excuse thereafter.”

The alternative, he said, would be to “pack our bags and search for another land, as is the sad, recurrent story in the arenas of jihad, because our enemy is growing stronger and his intelligence data are increasing day by day.”

After months of violence from Mr. Zarqawi and his allies, America and British military leaders will be hoping that his prophecy will come true.

In the Pentagon, there is a strong conviction that yesterday’s election will have a “transforming effect” on Iraq. They believe it will turn the tables on the insurgency, increase the legitimacy of the Iraqi government, and sow dissent among the insurgents. Just holding the election in time is seen as a bigger blow to the insurgents than any military operation.

“The election is a strategic prize,” said one senior Pentagon official. “Zarqawi tried to stop it. This is one for the good guys.

“In Afghanistan the elections changed everything. Now the Taliban is divided among those who want to fight the government and those who want a reconciliation.”

The idealists in the Bush administration see the election as the first and most powerful step in President Bush’s campaign to democratize the Arab world.

In London, though, officials are more cautious. “It shows we have a plan, and that we stuck to it,” said one Whitehall source. “Whether the plan will work is another matter.”

The British hope is that, at the very least, the Arab world will abandon its reticence about supporting the new authorities in Baghdad and help isolate the insurgents.

For all the jubilation yesterday, the poor turnout in the Sunni heartland shows how far Iraq has yet to go before it can stabilize and enjoy a representative government.

The insurgents may have failed to destroy the elections, but they have the power to convince or intimidate millions of Sunnis to stay away from the polls.

Sunnis form about one fifth of Iraq’s population. They made up the base of Saddam Hussein’s regime, and provide the backbone of the insurgency. The first task for the new government will be to ensure that the election, heavily weighted against Sunnis because of the boycott in central Iraq, does not further polarize Iraq and tip the country into civil war.

All sides point out that yesterday’s ballot was not the final word.

The new government will tell Sunnis that they still have a chance to join the political process in the next two elections – a referendum to approve the constitution in October and a new general election to elect a permanent government to be held in December.

But America, Britain, and the new Iraqi government still face another conundrum: The elected rulers cannot claim to be fully legitimate as long as American forces remain in Iraq, but they cannot survive without America’s protection.

The “exit strategy” will be a race to train enough Iraqi forces to take over the country’s security before any goodwill for the new government dissipates.

Prime Minister Blair has promised that America and Britain would draw up vague “timelines” for withdrawal, without setting a fixed “timetable” that would be seen as a victory for the insurgents. They have promised not to “cut and run.” But they know that they will soon have to start trying to creep away from Iraq.