-LRB- CNN -RRB- -- Mauricio Funes , a member of a political party that waged guerrilla war against the government 17 years ago , claimed the presidency of El Salvador on Sunday night . FMLN 's Mauricio Funes shows his ballot before voting Sunday in Antiguo Cuscatlan , El Salvador . `` This is the happiest night of my life , '' Funes told a jubilant crowd at his election headquarters . `` It 's also the night of greatest hope for El Salvador . '' With 90.68 percent of the votes counted , the FMLN party 's Funes had 51.27 percent , while the ARENA party 's Rodrigo Avila had 48.73 percent , the country 's Supreme Electoral Tribunal said . The final tally will be certified within 48 hours , the electoral council 's Walter Araujo said in a nationally televised news conference . Funes ' victory ended a 20-year hold on the presidency by the right-leaning ARENA . `` Now the ARENA party passes into opposition , '' Funes said . `` ARENA ... can be assured that it will be listened to and respected . '' Although polls had indicated the race had tightened considerably in the past few weeks , most analysts had predicted that Funes would win . `` It 's a sign that there 's democracy in that country , which is something the United States tried to foster , '' said Bernard Aronson , who as President George H.W. Bush 's assistant secretary of state for inter-American affairs from 1989-93 was heavily involved in ending El Salvador 's 12-year civil war . The FMLN , which is the Spanish acronym for the Farabundo Marti National Liberation Front , was formed in late 1980 as an umbrella group for five leftist guerilla organizations fighting a U.S.-backed military dictatorship . The guerrillas and the government signed a peace pact in 1992 and the FMLN became a legitimate political party . By some estimates , 75,000 Salvadorans died during the war . The new president will find `` a country that still retains a lot of bitterness , a lot of division , '' said Peter Hakim , president of the Washington-based Inter-American Dialogue policy institute . `` This country is completely divided , '' ARENA party official Adolfo Torres said on CNN affiliate TCS TV station Sunday night . The election , Hakim said , was `` an important test of how far El Salvador has come . '' The result also will be an important test of how far El Salvador will go . With an economy in deep trouble and neither party having enough seats to control the national Legislative Assembly , much will depend on the party that lost . `` Conflict occurs when one person wants to force a conflict , '' Hakim said . `` Compromise requires both sides . '' No one is certain how ARENA will handle the loss . `` That 's a big unknown , '' said Heather Berkman , a Latin America analyst with the consulting firm Eurasia Group . `` I still think they 'll play ball . They have an incentive to get along with the new administration . They certainly do n't want to be shut out of the process . '' Otto Reich , who served in high-level Latin American posts for Presidents Reagan , George H.W. Bush and George W. Bush , sees the possibility of a spirited fight from ARENA . `` If I had to guess , I 'd say ARENA will try to put democratic obstacles in the way of an FMLN consolidation of power , '' Reich said . Although ARENA , which are the Spanish initials for the Nationalist Republican Alliance , has come back from a 14-point deficit in some polls two months ago , Reich said winning a fifth consecutive term was `` swimming against the tide . '' `` People in El Salvador are weighing risks and opportunities , '' Reich said . `` They have an opportunity to replace a party with which they have gotten tired . '' Hakim also saw voter fatigue with ARENA , saying , `` One party has managed the country forever and ever . '' Many of the 2.4 million Salvadorans who voted weighed competing doubts . `` The uncertainty is that the FMLN has never been in power , '' Berkman said . But voters also asked themselves , she said , whether they were `` better off than they were five years ago , 10 years ago . '' Avila , she said , could not run on a message of change . Funes ' message of change and putting new people in power was more effective . Since the war ended , Salvadorans have mostly supported ARENA because of concerns over the FMLN 's left-wing agenda and the group 's guerrilla background . There also have been outside influences . `` The country has been afraid to vote for the left because of fears from Washington , '' Larry Birns , director of the nonprofit Council on Hemispheric Affairs , said recently . With the election of Barack Obama as president of the United States , Salvadorans may expect a different attitude from Washington . El Salvador , Colombia and Peru have been the United States ' closest allies in Latin America . Birns calls the three nations `` Washington 's street-corner guys . '' With an FMLN victory , El Salvador joins other Latin American countries that have elected leftist leaders in recent years -- Venezuela , Bolivia , Nicaragua , Argentina , Honduras , Guatemala , Ecuador and Brazil . But Berkman and others warn that the United States must not lump everyone together . `` People tend to look at the left in Latin America and oversimplify it , '' Berkman said . `` There 's the good left and the bad left . '' Or as Aronson put it , `` There 's leftists , and there 's leftists . '' Aronson sees two types of leftist governments in Latin America : `` institutional '' governments like Brazil 's that `` have made peace with the free market '' while still championing social programs , and populist , more-radical governments like Venezuela 's . Analysts are not sure what to make of Funes , a former freelance journalist for CNN en Español who is projecting a moderate image . `` The FMLN did something very clever , '' Reich said . `` They put somebody at the head of the party who is not a guerrilla , not a terrorist . '' Even the FMLN may not know what to expect from Funes . Berkman calls it `` an issue of uncertainty '' between the former journalist and the former guerrilla group . `` There 's a lot of unknowns about how the relationship between Funes and the FMLN will proceed , '' she said , adding that she will watch his Cabinet picks and whether he brings in people from other parties . Funes ' victory was a defining moment for the FMLN . `` It 's an important transformation , '' Hakim said . `` The ex-guerrillas have to make a decision : Are they going to try to bring about revolutionary , radical change or manage the whole country and have step-by-step reform ? '' Aronson sees it as `` a test of whether they will be pragmatic or ideological . '' The FMLN may not have a choice but to be pragmatic . The party holds 35 seats in the 84-member National Assembly . ARENA has 32 seats . Forty-three votes are needed to pass most legislation and some measures require `` supermajority '' approval of 56 votes . That means that , if ARENA and the FMLN can not agree on a measure , they have to look to one of the minor parties for support . The PCN , which is the National Conciliation Party , has 11 seats and could emerge as a power broker . Two others parties hold six seats . `` It is in the PCN 's interest to play ball as well , '' Berkman said . `` The PCN will act as a moderating force . '' Berkman also said the FMLN will likely take a moderate approach because the nation relies too much on outside investments and remittances from Salvadorans living abroad for the former guerrillas to adopt too much of a radical approach . But Hakim worries about something else . `` I think ARENA may be prepared for this -LSB- loss -RSB- , '' he said . `` I 'm concerned that the FMLN may not be prepared to govern . ''