The effort now appears to be one of several miscalculations in a high-stakes US strategy to use bombing, secret contacts and inducements — including cash payments — to key Iraqi leaders to quickly overthrow Saddam.

“We underestimated their capacity to put up resistance,’’ said a Bush administration who requested anonymity. “We underestimated the role of nationalism. And we overestimated the appeal of liberation.’’

US officials note that the war is just a week old, and they say that the sentiment among Iraqi military leaders could change quickly if Saddam’s forces around Baghdad are routed by American-led troops.

But a US intelligence official said no cracks have appeared in Saddam’s command structure as American and British troops fight their way toward the capital.

“I think the inner circle are in it for the long haul,’’ the intelligence official said Thursday. The estimated two dozen members of Saddam’s inner command include his two sons, Uday and Qusai, other members of his extended family and ruling Arab Socialist Baath Party stalwarts who have survived numerous purges.

The US effort to encourage defections, run jointly by the Pentagon and CIA, has been scaled back sharply since last weekend. “The negotiations went nowhere,’’ said a former senior CIA official. “All of them have proved futile.’’ He and other experts on Iraq said using telephones, cell phones and e-mail or relying on Iraqi defectors to contact senior Iraqi officials was problematic from the start because Saddam’s secret police and spy services tightly monitor electronic communications in the country.

The official, and others willing to talk about the effort, requested anonymity because of the sensitive topic.

The effort may have had a second goal, they said. It might have also been designed to cast suspicion on Saddam loyalists in hopes of sowing top-level turmoil. Saddam has imprisoned or killed anyone suspected of disloyalty in the past, and he crushed two coup attempts backed by the CIA in the mid-1990s.

In the Afghanistan war, the CIA disbursed millions of dollars in cash to buy information or loyalty from local warlords. Intelligence officials declined to say what they have offered to Iraqi leaders, but they made it clear that they are prepared to cut deals.