Eighteen years after the end of a civil war viewed by leading 1980s US policy-makers as nothing more than another Soviet-US proxy war, the candidate of the former guerrilla movement, FMLN, has won El Salvador’s presidential election.

At latest check of La Prensa Grafica, the FMLN’s Mauricio Funes had 51.3% of the votes in the two-candidate race, with almost 91% of votes counted. So it was no landslide, but when I asked yesterday if reports of very high turnout (by Salvadoran standards) indicated a possible leftist landslide, I really should have asked if it indicated a “massive swing.” Given the polarization of the country, and the fact that the FMLN in January’s legislative elections had won its highest percentage ever–by far–at 42.8% of the vote, a landslide (which I would take roughly to mean 55% or more in a 2-way race) was never realistic.

It was, however, a massive swing. The FMLN had managed less than a third of the vote in the one two-candidate presidential race it previously participated in, the 1994 runoff. In both 1999 and 2004 the ARENA candidate had won a first-round majority with the FMLN managing only 29% and 36%, respectively.

I will admit to some surprise that, with turnout rising so much, ARENA could still manage to come so close to half the votes. That is a good sign: both major parties were able to mobilize new voters, and to break their near-complete dependence on the wartime polarization. It is hard to exaggerate how important this election outcome is for Central American history and for post-civil-war democracies more generally. It marks the first real alternation in power in El Salvador’s history (not to trivialize the Christian Democratic presidential victory of 1984, but that happened under decidedly ‘special’ circumstances of US sponsorship).

Now comes the hard part: governing. This election gives the Salvadoran left a chance, but dealing with the divided assembly will not be easy for Funes. In January’s election, the FMLN won 35 seats, placing it 8 seats shy of a majority in the single chamber. The remnant of the Christian Democratic Party (PDC) has only 5 seats and a small centrist party 1.

There is simply no way that Funes can craft majorities for any proposed statutory changes without votes of the smaller right-wing party, the PCN, which has 11 seats. There is rich irony in that, as the PCN was the party of the governing landlord-military alliance against which the FMLN’s precursor organizations initially rebelled. The PCN has normally been an ally in congress of ARENA, although the PCN has on occasion joined with the FMLN. One prominent item of cooperation I recall from some years ago was on a proposal to forgive agrarian debt. That measure passed with the support of the FMLN, PDC, and PCN. It was vetoed by the president, and because it takes a two thirds vote to override a presidential veto and because ARENA held exactly one third of the seats, plus one, at the time, the bill died. The FMLN will need to work with the PCN again, and I expect the latter to be willing to bargain in order to preserve its place in a party system whose balance is now titled against it.

The presidency of El Salvador is by no means one of the strongest constitutionally in Latin America, but it is far from weak. It would be nearly impossible for the ARENA and PCN to legislate over the head of the executive, even if the PCN wanted to try, and despite these parties holding a joint majority of seats. The presidential veto would prevent it, and the FMLN has enough seats to sustain vetoes. More importantly, when the president of El Salvador vetoes a bill, he has the right to amend it. Stronger than a “line-item” veto, this veto permits the president to act as if he were a unipersonal revisory legislative chamber. By crafting an alternative bill to present to the Legislative Assembly after rejecting their proposal, he can bring the outcome far closer to his own preferences than if his veto strictly amounted to a choice between the status quo and the proposal passed by the legislature (as with the “package” veto of the US president).

The legislative balance of party forces, the PCN’s need to distinguish itself from ARENA now that the latter lacks control of the executive, and the constitutional powers of the presidency all give the FMLN a real opportunity to compromise with other political forces for the benefit of the Salvadoran populace.

The Cold War is over at last. The Salvadoran people have won.