Guatemala's new president, an admitted killer who has promised to crack down on soaring crime, was sworn into office today by the new president of Congress, a former military dictator accused of presiding over indiscriminate killings during the country's decades-long civil war.

In his inaugural speech, President Alfonso Portillo, a populist attorney and economist, emphasized the problems posed by class discrimination in Guatemala and returned often to themes that won him the election, saying his administration will reduce impunity for criminals, fight discrimination, strengthen democracy and push for social and economic reforms to help the poor and disenfranchised.

"For my part, I guarantee a government for the greatest participation of the citizens," Portillo said. "In a country like ours, confronted with inequity, violence, discrimination, intolerance, plundering and impunity, democracy is unavoidable and urgent."

Portillo, a member of the right-wing Guatemalan Republican Front, was sworn in by his political godfather, former army general Efrain Rios Montt, who headed a military government in 1982-83 and founded the party. During his dictatorship, Rios Montt, now 74, fought a Marxist insurgency with a brutal military campaign in which hundreds of villages were razed and tens of thousands of civilians were killed, many of them poor Mayans seen as rebel supporters.

Rios Montt--a born-again Christian who broadcast weekly sermons during his 17-month rule--was banned by the Guatemalan constitution from seeking the presidency because he came to power in a military coup d'etat. But in November his party, capitalizing on nostalgia for the law and order he imposed and the corruption-free government he led, won a majority of 63 in Guatemala's 113-seat Congress. Today he was elected president of the legislature for the first year of its four-year term.

Portillo, 48, wrested the presidency from the incumbent National Advancement Party with a landslide victory in a two-man runoff on Dec. 26, taking advantage of widespread anger over soaring crime and poverty and disgust with the outgoing president, Alvaro Arzu, who was viewed as arrogant, elitist and corrupt. Under Guatemalan law, presidents serve only one four-year term.

In a broader sense, according to some political analysts, Portillo seems styled after other populist leaders in Central and South America who have shot to power on the depth of voter frustration with the practical results of democratic and free-market reforms. In many countries, the changes have helped spur growth and cool hyperinflation, but have not stemmed poverty and corruption or delivered a better standard of living for the poor.

The disenchantment is particularly acute in the old Cold War battlegrounds of Central America, where Guatemala, Nicaragua and El Salvador were devastated by civil war in the 1970s and '80s and where citizens expected a substantial "peace dividend" after arms were laid down. About 200,000 were killed during the 36-year war in Guatemala, a country of 11 million that returned to civilian government over a decade ago and where the war officially ended four years ago. Yet 80 percent still live in poverty, the per capita income is about $1,000 a year and corruption is pervasive.

"There is a sense that democracy has not delivered the goods," said George R. Vickers, head of the Washington Office on Latin America and a member of the U.S. delegation to today's inauguration.

"The political system in Latin America is in deep crisis," said Frank Larue, head of Guatemala's Center for Human Rights Legal Action. "People are fed up, so there's a trend to reject the system because it's not offering anything new, just traditional politicians."

Portillo's 68 percent landslide against a former Guatemala City mayor came despite--some say because of--revelations that he shot and killed two men in a drunken brawl in Mexico 17 years ago, then fled out of fear that he would not get a fair trial. Rather than playing down the incident, Portillo, who said he acted in self-defense, incorporated it into an advertising campaign, with a TV announcer intoning: "Portillo: If he can defend himself, he can defend you."

A Mexican judge formally closed the case in 1995 after the statute of limitations expired.

The killings and the way Portillo exploited them in the campaign, combined with his populist leanings and ties to Rios Montt, have prompted concern about how he will conduct business as president. Some recall the slogan from his failed 1996 presidential bid: "Portillo the presidency, Rios Montt the power." The slogan tapped the popularity the ex-dictator still enjoys for pacifying the country, despite the excesses of the military under his leadership.

Others say Portillo and his relationship with Rios Montt are more complicated.

An economist, attorney and former professor, Portillo spent about 15 years in exile in Mexico and supported Guatemala's leftist guerrillas. The son of a rural teacher, he reportedly admires British Prime Minister Tony Blair and the late revolutionary leader Ernesto "Che" Guevara. He was elected to Congress as a centrist Christian Democrat in 1990, then switched to the Guatemalan Republican Front in 1995 to run for president.

Although he stood in for Rios Montt as the party's presidential candidate when the former dictator was declared ineligible to run in 1996, Portillo spent the past four years campaigning hard and building his own constituency. Recently, he said he owes his election to no one and will call his own shots in office.

Portillo is forming a broad coalition in his cabinet, recognizing the necessity of negotiation and compromise. His vice president is a strong Rios Montt supporter; the new foreign minister was Rios Montt's personal attorney; and the former dictator reportedly was allowed to veto Portillo's first choice for defense minister--a general who helped overthrow Rios Montt in 1983.

On the other hand, Portillo vetoed Rios Montt's daughter as foreign minister. He also has brought into his cabinet a wide array of independent leftists, academics, indigenous people and human rights activists, including a Mayan woman who served on Guatemala's truth commission, which blamed Rios Montt's government for numerous atrocities.

How the lineup will jell into a government is still unclear, but Portillo must move quickly to address the country's vexing needs or his support could fade, especially if Congress turns hostile. Voters turned against Arzu even though he presided over the end of the war, tripled the number of police officers and built hundreds of roads, schools and clinics.

Portillo has promised to implement peace accords and truth commission recommendations that Arzu ignored. He will also have to consider structural changes to help address Guatemala's vexing problems, including a currency in steep decline, a banking system in crisis, high budget deficits, a corrupt judiciary and a dysfunctional tax system.

But analysts said that improvements in those areas will hardly begin to address the unfinished business of democracy that remain Guatemala's biggest challenges: discrimination against the Mayans, a powerful business community that refuses to be taxed and some of the hemisphere's most inequitable wealth and land distribution.

CAPTION: Alfonso Portillo, right, is sworn in as president of Guatemala by Gen. Efrain Rios Montt, his mentor and the new president of Congress. In his inaugural address, Portillo called democracy "unavoidable and urgent" in the face of staggering problems.

CAPTION: Guatemala's former dictator, Gen. Efrain Rios Montt, right, greets legislator Jorge Passarelli after Rios Montt was elected president of Congress.