Salvadoran Opposition Party Breaks Up : Latin America: Bitter split of ex-rebels echoes crisis within the political left throughout region.

The guerrillas who steadfastly held together through 12 years of civil war against powerful U.S.-backed forces, then in peace became this country’s leading opposition politicians, formally split Tuesday, leaving the once-formidable left here in disarray.

Riven by bitter differences over direction and philosophy, the Farabundo Marti National Liberation Front (FMLN) divided into at least two groups with the withdrawal of one of its principal factions.

“The FMLN was an instrument created to make war,” said Joaquin Villalobos, leader of the faction that abandoned the FMLN. “In the current conditions, the Front no longer has political viability as an electoral instrument and should pass into national history.”

The split, announced by Villalobos, follows months of acrimonious debate over the role of the FMLN as an opposition party in the post-Cold War era. It echoes a crisis experienced by the left throughout Latin America, where onetime guerrilla armies are struggling to come to terms with the demise of their Soviet Bloc sponsors and the challenge of operating under the democratic rules of civilian politics.

The fracturing of the Salvadoran left drastically weakens any political opposition to the conservative government of President Armando Calderon Sol, giving it free rein as its own extreme right wing battles for more power.

It also leaves unprotected the U.N.-brokered peace accords that ended the war two years ago and promised wide-ranging political and judicial reforms, many of which are still incomplete. With the opposition largely impotent, and the international community losing interest--the U.N. mission closes in four months--there is no one to see that the accords are implemented.

The FMLN was formed in the late 1970s at the behest of Cuban leader Fidel Castro, who recommended that the five leftist guerrilla factions fighting the right-wing, army-dominated Salvadoran government join forces.

Each of the factions maintained its own identity throughout the war and controlled distinct territory. But they presented a united front in military strategy, bedeviling the better-equipped, better-financed Salvadoran government forces, who had the backing of billions of American dollars.

The FMLN fought the U.S.-trained forces to a standstill by 1991, a situation that forced the two sides into U.N.-sponsored negotiations that ended the war. The FMLN agreed to disarm and become a legal political party in exchange for broad reforms.

The faction that announced its withdrawal from the FMLN on Tuesday was not the largest but was considered the strongest militarily. Its leader, Villalobos, was credited with devising the FMLN’s most successful military strategy.

But since the war’s end, Villalobos has moved most swiftly toward the center, reanointing his faction as a social democratic party and often entering into political compromises with the right. He argues that he is modernizing his party and making it a workable organization in light of the reality now.

Other FMLN factions, however, say Villalobos is a sellout and an opportunist. They argue that they are fighting for many of the original goals of the guerrilla movement, such as better conditions for the poor, that Villalobos and his associates have long abandoned.

El Salvador’s left was further forced into self-analysis after its overwhelming loss in presidential and legislative elections earlier this year.

The elections marked the first participation of the left, and, while the right scored major victories, FMLN candidates won several seats in the legislative assembly and in city halls.

With the formal rupture of the FMLN, however, it seems doubtful that the left can act as a unified bloc in the legislature.