Hundreds of thousands of people have been taking part in what is being described as the biggest ever protest in Bolivia's main city, La Paz.
People from La Paz say switching the capital would be divisive
They are angered by a proposal to transfer the executive and legislative branches of government to Sucre.
Sucre served as the sole capital until 1899. Since then, the two cities have shared the title.
The latest proposal was put forward by opponents of the country's President, Evo Morales.
They have been seeking greater autonomy for the wealthier eastern provinces, as part of the ongoing rewriting of the Bolivian constitution.
They argue that Sucre, which is in the centre of the country and is the seat of the country's judicial branch of government, is better placed to serve as a capital than La Paz, which is on the western edge of Bolivia.
But those in favour of La Paz say switching the capital from Bolivia's largest city, with a population of 1.7 million, to Sucre, population 250,000, would be expensive and divisive.
Sucre was the site of Bolivia's founding in 1825 and its sole capital until losing a brief civil war to La Paz in 1899.
Its demand for the return of the seat of government has fuelled a regional rivalry between President Morales' supporters in Bolivia's poor western highlands and his opponents in the more prosperous east.