George Mitchell is in the Middle East, pressing for peace. His planned itinerary brackets Israel and Palestine with a start in Abu Dhabi and Syria and a conclusion in Bahrain and Egypt. The Obama administration’s determination to revivify the Israeli-Palestinian peace process is further indicated by the arrivals in the region next week of Secretary of Defense Robert Gates, National Security Adviser James Jones, and special Middle East adviser Dennis Ross. President Obama has replaced the Bush policy of hands-off with a gloves-off readiness to push all parties hard.

The destitution of Gaza remains the largest, and most unaddressed, problem between Palestinians and Israelis. Progress toward reconciliation there remains remote, but it presumes prior accommodation between Israel and the Palestinian Authority in the West Bank. That prospect, though, has become ever more nettlesome in recent days because of tensions over Jerusalem. This week, the sacred city comes into the center of Jewish awareness as Jews everywhere observe the holy day of Tisha B’Av, the commemoration of the destructions of the Temple. Those calamities, as this Christian understands them, define not only the place of grief in the Jewish soul, but also the Jewish capacity for reinvention and survival. To the extent that the on-again, off-again peace process has offered prospects of reinvention and survival to both Israelis and Palestinians, a new conflict over Jerusalem now threatens to join the enforced misery of Gaza as a looming deal-breaker.

Unlike his predecessor, President Obama is demanding of Israel that it live up to the requirement of the 2003 Road Map toward a two-state solution, namely a total “freeze’’ on all settlement activity. (According to one Israeli human rights group, since 2003 the Jewish settler population in the West Bank grew from about 211,000 to almost 290,000. Additionally, the settler population in East Jerusalem has grown to more than 190,000.) Tensions between Israel and Washington flared this month over planned Israeli expansion of settlements in East Jerusalem, with Prime Minister Benjamin Netanyahu defiantly declaring his intentions to go ahead. The steady Jewish population increase in the disputed part of Jerusalem occurs in combination with the Jerusalem municipality’s ongoing demolition of Palestinian homes, constructed without permits. Thousands of Palestinian homes are under the demolition order. The two-state solution assumes that East Jerusalem will be the capital of the Palestinian state, but that prospect is daily undermined by the ongoing creation of “facts on the ground’’ by Jewish settlement and Palestinian displacement. “A united Jerusalem is the capital of the Jewish people in the State of Israel,’’ Netanyahu declared this month, “and the sovereignty of the city is not subject to appeal.’’

For a decade or more there has been a majority consensus among Israelis and Palestinians that Jerusalem will be the capital of both states, with some combination of east-west distinction, and overlapping sovereignty (Israel sovereign over the Western Wall and the Jewish Quarter of the Old City, Palestine sovereign over the Muslim Quarter and the Noble Sanctuary). The vision assumes a side-by-side accommodation, no return to the barbed-wire border of the pre-1967 era. In that sense, a shared Jerusalem was to be, in a phrase of President Bill Clinton’s formula, “an open and undivided city.’’ That was the ideal to which candidate Barack Obama had referenced when he declared before a Jewish group in 2008 that Jerusalem “must remain undivided.’’ That he was misunderstood by Jews and Palestinians alike as echoing a minority Israeli wish to preempt Palestinian authority in Jerusalem showed how far the “shared Jerusalem’’ concept had eroded. It must be restored.

The Obama administration’s initiatives are crucial. As Arab governments are pushed to take timely steps toward normalization with Israel; as negotiations with Syria get back on track; as the Palestinian Authority is pressed to resume peace talks; as the Hamas rocket truce in Gaza is reinforced - focus on Jerusalem must still be maintained. The settlement freeze must be absolute, especially in Jerusalem. The demolition of Palestinian houses must be halted, especially in Jerusalem. “Two states for two peoples’’ is Obama’s watchword. Netanyahu has affirmed it. But that hope requires agreement on the one city both peoples love. Jerusalem is sacred, but so is the obligation now to share it.