LA PAZ, Bolivia (AP) _ Bolivia's new president promised early elections and worked Saturday to form a transition government as his predecessor fled to the United States, driven from office by a month of violent demonstrations.

President Carlos Mesa _ the former vice president inaugurated late Friday after Gonzalo Sanchez Lozada resigned _ takes over this struggling Andean nation amid its worst crisis in decades and after rioting that left 65 people dead.

``We have to respond to one of the biggest challenges in our history. If you all can't help me there is no way we can crawl out of this,'' the new president said late Friday.

Mesa, 50, held talks at his home Saturday with labor and government officials, and said his administration would be an interim one, even though law calls him to serve out the rest of the ex-president's term, until August 2007.

The departure of the 73-year-old Sanchez de Lozada brought a degree of peace: Soldiers and police withdrew from streets in the capital, La Paz, and other cities early Saturday. Merchants and vendors reopened for business. Governments around Latin America offered support for Mesa.

``Popular clamor defeated Sanchez de Lozada,'' a headline in the El Diario newspaper declared. ``Democracy is unharmed.''

Still, Mesa inherits a climate of social unrest over the ex-president's free-market economic policies, seen as widening the divide between rich and poor. Unemployment is at 12 percent and most Bolivians earn around $2 a day.

Poor Bolivians _ Indian and labor leaders _ spearheaded the street demonstrations that started in mid-September and swelled into marches by thousands. People built road blocks that caused food shortages and isolated La Paz from the rest of the country. Protesters with sticks and rocks clashed for days with soldiers sent to drive them away.

The riots erupted over Sanchez de Lozada's plan to export natural gas to Mexico and energy-starved California. The ex-president had hoped to tap the country's expansive natural gas reserves to boost economic growth and lift South America's poorest country out of years of economic stagnation.

Many Bolivians were particularly angry that the fuel might be shipped through a port in neighboring Chile instead of through Peru, another option. Bolivia lost its coastline in an 1879 war against Chile, and resentment is fierce to this day.

Officials involved with the $6 billion export project, led by Repsol YPF of Spain and British Gas Petroleum, said Saturday they hoped it would move forward.

``The upshot of the project will depend on when the dust settles,'' said Chris Carter, a spokesman for BG Group in London. ``We're still there doing what we can.''

Meanwhile, the disgraced ex-president sought refuge in the United States, where he was raised and educated, amid concerns for his security in Bolivia. He touched down first in Florida before flying to Washington, said Bolivian General Consul Moises Jarmusz Levy, in Miami.

Abandoning the presidential residence in a military helicopter, Sanchez de Lozada became the fourth Latin American president driven from office by widespread protests in recent years.

Ecuador's Jamil Mahuad, Peru's Alberto Fujimori, and Argentina's Fernando De la Rua were all unseated by outpourings of public anger over U.S.-backed free-market economic policies.

Bolivia's future has regional implications, and Brazil and Argentina both sent high-level envoys here Friday night after the president resigned, according to Brazilian government official Gilberto Carvalho.

Brazil, South America's biggest economy, relies on Bolivia as an export route to Asia and for the bulk of its natural gas. Bolivia also is an associate member of Mercosur, the trade block made up of Argentina, Brazil, Paraguay and Uruguay.

The United States also sent a team to assess security for embassy staff in La Paz. The State Department said Saturday that it regrets the events that led to fall of the government and commended Sanchez de Lozada ``for his commitment to democracy and to the well being of his country.'' It had no immediate comment on his arrival in the United States.

Mesa, a former television reporter and respected historian, could get an early boost because of his status as a political independent, observers said. But that also means he lacks a political base, observers said.

``Mesa is an outsider, which is helpful in terms of connecting with the disaffected groups,'' said Donna Lee Van Cott, a Latin American political expert at the University of Tennessee.

``But it will be very difficult to govern in Congress. It's going to be very difficult because of the demands of the indigenous sector. They've been deprived for so long, it may be difficult to negotiate with them.''

In a show of unity, one prominent protest leader already threw his support behind the new president.

``We will give the new president some breathing room so he can get organized and deliver on his promises,'' said Evo Morales, an opposition congressman who rallied Indian groups, peasants, miners and others against the previous government's economic policies.

Regional leaders also gave their support. Chilean President Ricardo Lagos said, ``We would like to collaborate with the new authorities, with the new president and to wish him success in his new duties.''

Venezuelan President Hugo Chavez also offered ``to help however we can'' to the new Bolivian leader.