Bolivians will vote on a new constitution Sunday that grants rights to gays and lesbians in the country while defining marriage as a heterosexual union.

The Bolivian constitution already bans gay marriage. In 2007, lawmakers added the provision to the constitution.

The vote replaces the current 1967 charter and gives leftist President Evo Morales the right to run for a second five-year term. It would also give greater voice to the indigenous people who make up the majority of the country and grants the central government greater power.

“Once approved, this will be the refoundation of Bolivia and the refoundation of a new state where there will be equality and we will all have the same rights and the same obligations,” Morales said at a rally in the country's capital, La Paz.

The document is being decried by churches that see it as opening the door for gay marriage. There are neither laws against being gay, nor laws protecting gays and lesbians in the South American country.

However, the new constitution would prohibit discrimination based on sexual orientation, while defining marriage as a union “between a man and a woman.”

The new text no longer specifies Roman Catholicism as the sole state religion and outlines broad new rights for Bolivia's Indians.

Indigenous people, who make up the majority of the 9 million people living in the landlocked country and view Morales as an indigenous hero, are expected to favor the new document.