A PAZ, Bolivia, Aug. 4 – Bolivia's Congress ended a presidential tie today, picking an American-educated millionaire, Gonzalo Sánchez de Lozada, to lead the country as it confronts economic malaise and growing social unrest.

Mr. Sánchez de Lozada, a mining executive and a political centrist who was president from 1993 to 1997, won by a congressional vote of 84-43 over Evo Morales, a radical Indian leader of Bolivia's coca growers.

The men were the top two vote-getters in a national election in June, but neither won an outright majority, forcing a vote in Congress.

Two congressman left their votes blank today, while 26 voted for Manfred Reyes Villa.

The Legislature convened Saturday and debated for more than 24 hours. Each of the 157 members gave a speech, with some wearing multicolored Indian clothing and speaking in indigenous languages. Others chewed coca leaf, the base material of cocaine but also a part of centuries-old Indian culture in the Andes.

Mr. Sánchez de Lozada assured his victory in the vote more than a week ago by securing an alliance with his rival, Jaime Paz Zamora, a leftist former president.

Known by the nickname "Goni," Mr. Sánchez de Lozada spent most of his youth in the United States and still speaks Spanish with an American accent that is often the brunt of jokes among Bolivians. He grew up in Washington, where his father was a diplomat, and later studied philosophy and English literature at the University of Chicago.

Mr. Sánchez de Lozada will face an opposition galvanized by the blunt-talking Mr. Morales, whose Movement to Socialism party has given Bolivia's downtrodden Indian majority a strong political voice.

Mr. Morales fiercely opposes a program backed by the United States that has wiped out most coca plantations, while Mr. Sánchez de Lozada has vowed to continue the eradication effort. Washington heralds the program as a shining success in its war on cocaine, but eradication has led to deadly clashes between farmers and security forces.