NAHARIYA, Israel -- Hope for the release of Sgt. Gilad Shalit, held by Hamas since 2006, has become enough of a cause célébre to bring Israel near the edge of a trade long considered taboo: releasing as many as 1,000 Palestinian prisoners in return.

The deal still may not happen. Prime Minister Benjamin Netanyahu has been holding marathon meetings this week with half-a-dozen cabinet ministers to discuss a possible swap to end the 3 ½-year ordeal of the captured soldier, now 23 years old.

On...