“Now, it’s only a municipal boundary,” he said. “But the whole world gets used to it — that there’s something else that’s Al Quds. And very quickly, the perception would be that Al Quds is not Jerusalem. And then, to do the diplomatic move of severing it and handing it to the P.A. would be much easier.”

“And who would’ve been the ones who allowed that?” Mr. Bennett added. “The right wing. They’d say, ‘You’re the guys who legislated this.’”

Mr. Bennett was a co-sponsor of the bill that contained the language allowing the Jerusalem map to be redrawn, but he was responsible for a different part of it, which raised the threshold for ratifying any peace deal involving ceding parts of Jerusalem. It requires 80 votes out of 120 in the Knesset, a forbidding supermajority.

That part of the bill was enacted, prompting howls from the left and a broadside from the Palestinian Authority, whose top spokesman said Tuesday that it amounted to “declaring war on the Palestinian people and their political and religious identity.”

The measure on redrawing the Jerusalem city map, by contrast, would have affected only a few areas, like Kufr Aqab and the Shuafat refugee camp, that have been largely abandoned by the city because of concerns for the safety of its employees outside the security barrier. This has turned them into teeming boomtowns of illegal construction, where estimates say the population has soared to between 70,000 to 150,000 people.

Hagai Agmon-Snir, director of the nonpartisan Jerusalem Intercultural Center, said the possibility of excising those areas from the city had set off alarm bells across the political spectrum. “There’s a consensus among all Jerusalem activists, right and left, that this is not a good idea, because it’s not stable,” Mr. Agmon-Snir said.

Creating a new local governing body would take years, and in the meantime, the Jerusalem municipality “will not invest a cent there,” he said. Before any new local government could get up and running, he said, “Kufr Aqab and Shuafat are sure to collapse.”