Politics is the art of addition, of winning votes, and of assembling coalitions. Subtracting and dividing are losing strategies - or so one would think.

But division did pretty well in El Salvador, which held its presidential election last Sunday. National Republican Alliance (ARENA) candidate Tony Saca won, not so much because his right-wing party had moved toward the center following El Salvador's civil conflict in the 1980s, but because opponent Schafik Handal of the Farabundo Martí Liberation Front (FMLN) took his campaign back to his party's roots on the hard Left.

Handal's anti-U.S. rhetoric scared independent voters and even his own supporters. El Salvador's economy depends heavily on some $2 billion in remittances that its citizens send home every year from the United States - where about one in four now live. Overall, he obtained about 36 percent of the vote from core party members, but Tony Saca outpolled him by two-to-one even in municipalities under FMLN leadership.

Handal promised a retreat from a new free-trade pact with the United States and a realignment with Cuba while Saca innocuously offered to bolster public security, improve tax collection, and modernize the public-health system. But Saca also spoke to fears that his rival would govern as a populist autocrat and reverse many of El Salvador's free-market gains since the government and the guerrillas signed a peace accord in 1992.

A record 65-percent participation rate suggests that many citizens responded to that message. ARENA won every "department" (El Salvador's equivalent of a state) and nearly every municipality.

While the politics of polarity may have put another conservative at the head of El Salvador's government, there will be attendant costs. One is El Salvador's shrinking political center. Both ARENA and the FMLN were born during El Salvador's civil war in the 1980s, where they represented extremes of the right and left. Since peace broke out, however, they have converged toward the middle.

Despite gains in mayorships and the national legislative assembly, the FMLN has lost every presidential race since 1989. Attempting to do better this time, party leader Handal reversed the FMLN's moderate course, purged centrist reformers, and decided to run for the top job himself on a more hardline platform.

Had San Salvador's effective former mayor Hector Silva been the party's candidate, he might have won. But, forced out of the FMLN in 2002 by Handal's retrograde agenda and temperamental personality, he ran on the Center Democratic Union ticket. Followers viewed the switch as disloyalty and awarded him only four percent of the vote. No viable party therefore occupies the central ground between the dueling ARENA and FMLN blocs.

Unfortunately, polarized politics leads to hyperbolic arguments and legislative roadblocks. In a grudging concession speech, Handal promised "resistance without quarter" in opposing Saca's initiatives and withholding legislative votes for the U.S.-Central America Free Trade Agreement. That is no idle threat. The FMLN controls 31 seats in El Salvador's 84-seat National Assembly, while ARENA has only 27.

During its 24 years of existence, the FMLN has become a well-known brand and will not likely disappear. But whether Handal will now step down to allow more moderate leaders to take over is doubtful. In 1980, he was there in Havana when Fidel Castro urged El Salvador's fractious guerrillas to unite in single political and military fronts.

Tony Saca is already trying to reach out beyond ARENA to form an effective government. He told the newspaper Diario de Hoy that he wants a dialogue with all parties and agreement on a mutually satisfactory political agenda. He would do well to bolster the moderate Left by finding a role for some of its politicians in his administration.

For their part, U.S. officials should refrain from divisive rhetoric, lest it encourage a backlash. Before the election, lawmakers and Bush administration figures publicly warned that a Handal victory could damage relations. No doubt, Handal will use such comments to claim U.S. "intervention." Instead, Washington should be urging Salvadorans to build coalitions around common interests and to use non-partisan commissions to provide recommendations for difficult decisions.

Division and polarization claimed Cuba 45 years ago. Venezuela and Bolivia have become recent casualties. Meanwhile, former Sandinista commandante Daniel Ortega is attempting to polarize and divide Nicaragua. For the moment, El Salvador has escaped through an exemplary display of civic responsibility. But pressure for a rupture is building. Now is the time to channel some of that pressure in a positive direction.

- Stephen Johnson is senior policy analyst for Latin America at the Heritage Foundation, and visited El Salvador as an international observer during the March 21 presidential elections.