Aresounding win by Hamas in Palestinian parliamentary elections threatens to upend the Middle East peace process. The surprise victory confirms many of the more troubling speculations about the immediate impact of democracy in the region. But winning elections carries risk for radical groups, too: The day-to-day work of government is a new challenge and considerably more difficult than waging war. Hamas is better prepared than most organizations to take up that challenge, but it will be torn between its commitment to armed struggle against Israel and the need to better the lives of ordinary Palestinians. As a first step, it should renounce its militant wing and commit itself to peace with Israel.

Two sides exist in Palestinian politics: those committed to peace with Israel and those who are not, and those who demand clean government and those who profit from corruption. Hamas has not recognized Israel's right to exist and yet it provides Palestinians with many social services that the Palestinian Authority should deliver, but does not. Both have made Hamas popular. Up to now that popularity had never been tested at the ballot box because Hamas had refused to join democratic politics in Palestine, arguing that such a step would legitimate a political process with Israel that it opposes.

Sensing that the tide had changed, Hamas agreed to run in last week's election. While most observers predicted a strong showing by the group, none anticipated the result: a clear majority for Hamas. It won 76 seats in the 132-seat Parliament, giving it a majority and the right to form the next government. Fatah, which had ruled the Palestinian Parliament since it was formed -- and dominated the Palestinian movement since its inception -- claimed a mere 43 seats. Smaller parties won the remaining seats; four independents will back Hamas. By one measure it is a resounding mandate: Some 78 percent of the 1.3 million Palestinians cast ballots. In fact, however, Hamas polled less than a majority -- the voting system, and a fractured opposition, helped the group win so convincingly.