Reasons for optimism go well beyond the "good vibrations" of this week's summit in Sharm el-Sheikh, Egypt. The situation on the ground has calmed considerably since Jan. 9, when Palestinians elected Mahmoud Abbas as their leader. In late January, the Palestinian Islamic movement Hamas announced its readiness for a temporary cease-fire, and Ariel Sharon's government in Israel followed suit. That truce was formalized at Sharm el-Sheikh.

A notable (and helpful) sense of hope seems to have taken root. A poll of Israelis in late January found just under 80 percent support negotiations with Mr. Abbas, and 57 percent believe that this diplomacy could lead to peace. On the Palestinian side, Hamas supporters turned out in droves in two rounds of municipal elections since late December. On Feb. 6, thousands of them braved harsh rain to take part in a peaceful mass demonstration in Gaza that urged Israel to the release of Palestinian detainees.

The depth of feeling - on both sides - on the release of detainees is just one indication of how tough the negotiations ahead might be. But at least Hamas seems committed, for now, to pursuing its goals through the ballot box and peaceful mass action. Those, unlike suicide bombings, are the tactics of hope for a worthwhile future and trust in the basic value of "people power."

Such attitudes are especially important at a time of tough negotiations. How can the new hopefulness be strengthened in the weeks ahead?

The US will play a crucial role. Since the 1970s, Washington has dominated the brokering of all Israeli-Arab accords. This may be the hardest one of all. President Bush has set clear goals for himself - as coathor of the road map for peace two years ago, and more recently as a declared supporter of a viable, independent Palestinian state. (To be viable, the state needs both a solid and contiguous land base and full political and economic independence.) Meanwhile, American troops and other assets are spread in a very vulnerable way throughout the Middle East. If it looks as though Mr. Bush is using his new high-profile diplomacy to push forward only Israel's interests, Americans might pay the price. By contrast, palpable movement toward the stated goal of the road map - conclusion of a "permanent status agreement" between Israel and Palestine in 2005 - could vastly improve Washington's relations with most of the world's nations, both in and outside the Middle East.

Implementation of the road map is still, sadly, far behind schedule. But with the active intervention of the US and the plan's three other sponsors - the United Nations, the European Union, and Russia - most of its preliminary steps can be consolidated, making the final goal still attainable this year. It helps that the Clinton Plan of late 2000 and the Geneva Accords of 2003 have sketched out what a workable two-state outcome can look like.

Audacious? Yes. And, it would be highly ironic if longtime Israeli tough guy Mr. Sharon and a Palestinian coalition clearly including Hamas are the parties that end up making peace. For both sides, this would be a "Nixon to China" phenomenon. But it could happen.

And if it fails? Then, the prospect is extremely grim. We saw in the 1990s that when hopes for peace are raised, then dashed, that can unleash atrocious violence in both societies. For the sake of both peoples, the present hopes for a livable peace must be fulfilled.

• Helena Cobban is working on a book about violence and its legacies.