Amir Peretz, the new leader of the Labor Party, deserves congratulations for his extraordinary victory over Shimon Peres in Wednesday's party primaries. Peretz, the outsider in every sense of the word, had the personal courage and fortitude to challenge the party establishment and face harsh and often insulting attacks. He is a Sephardi of Moroccan descent, he comes from the development town of Sderot, which he once headed, and the main plank of his agenda is social rather than diplomatic or military. Some commentators have even, exaggeratedly, compared his victory to the 1977 "political earthquake," when the Likud replaced Labor as the country's governing party for the first time. There seem to have been two main reasons why Peretz was able to pull off the upset. For one, he is 27 years younger than Peres, who was first elected party chairman almost three decades ago. Labor has fumbled around for many years searching for a leader of the younger generation to replace the Old Guard. None of the candidates picked to date had the stature, experience or solid party base to last long. After flirting with these alternatives for a few years, the party establishment felt it had no choice but to turn to Peres once more. However, a majority of the voters wanted something else. The other reason may have to do with the social climate in the country today. For many years now, Labor and the Likud have been rightfully perceived as the Tweedledee and Tweedledum of economic policy, both capitalist-oriented and out to primarily serve business and the upper middle class. Peretz offers a genuinely different agenda. In fact, his election marks the first time in decades that the two major parties will offer a choice of two radically different social and economic platforms to the electorate. Nevertheless, it is not clear how much support Peretz will win for his platform among the wider public. Labor's overall support is at an all-time low, largely as a consequence of abiding mistrust and disillusion with the Labor-trailblazed notion of feasible, substantive negotiations with the Palestinians. Peretz was able to register a relatively large hardcore of Histadrut supporters, who gave him a disproportional source of strength among the party rank and file. The question is whether there are more like that bunch of Peretz loyalists out there among traditional Labor voters and the population in general. Peretz will need many more if he is to become the viable leader of an influential party. For the moment, he faces the threat of being promoted to the rank of general and losing the army at the same time. First of all, it is possible that some of the Old Guard will desert Labor and join ranks with Prime Minister Ariel Sharon should he decide to abandon the Likud. There is also the possibility that traditional middle class voters, who, along with the kibbutzim, have been the backbone of the Labor Party, will find Peretz too socially radical and cast their votes for Shinui, Meretz, or Sharon, if he leaves the Likud. Obviously, Peretz will not be able to do whatever he wants. For the time being, he is outgunned and outnumbered by his powerful rivals in the party, including Peres, Ehud Barak, Matan Vilna'i, Dalia Itzik and Haim Ramon. They will try their hardest to rein in their emotional and fiery leader and bring him into what they believe is the moderate and responsible consensus. His first test could be the refusal of party leaders to resign from the government. Nevertheless, under Peretz, the Labor Party will present a true alternative to the Likud in both the diplomatic-security field and the social and economic sphere. And while the pros and cons of Israel's options in the first of these areas are already ceaselessly debated, his arrival on the political frontlines will likely galvanize a welcome public debate on the social and economic values and criteria which will determine the country's domestic policy. Given his stated desire to quickly lead Labor out of the coalition and into general elections, Peretz's success also potentially complicates life for Sharon. The prime minister will presumably now have less time than a Peres victory in Labor would have allowed him to decide whether to seek reelection from within the Likud or as the head of a new party.