Demonstrations have rocked Bolivia for more than two months. A longstanding political rivalry has boiled over, with supporters of the president and his chief opponent clashing in the streets. Protests have blocked the movement of goods, exacerbating fuel shortages. Some Bolivians lined up for days to buy gas.

The upheaval is part of a broad level of unrest across the Andean region of Latin America. Ecuador, Peru and Colombia — Bolivia’s neighbors to the west and north — are all facing significant levels of political turmoil, causing intense anger among their populations.

Behind the discontent in Bolivia is a rupture within the Movement for Socialism, or MAS, a leftist party that has dominated the country’s political landscape for two decades.

Bolivia’s president, Luis Arce, and his onetime mentor, former president Evo Morales, are fighting over the party’s leadership — and both insist that they will be the party’s candidate in next year’s presidential elections.

The turbulence reflects a steep decline in influence for both the leftist party and Mr. Morales, Bolivia’s first Indigenous president and a monumental figure in the country. He held office for 14 years — longer than any other leader.