Bolivia's polling stations opened Sunday morning for voters to participate in the South American country's nation-wide referendum, which will decide whether current President Evo Morales will be allowed to run for a controversial fourth consecutive term in 2019.

Morales, 56, is Bolivia's first indigenous president, and he has held office for 10 years. Having taken office in 2006, he won strong margins in the following residential elections, garnering 64 percent in 2009 and 61 percent in 2014. The Bolivian constitution currently only permits the president and vice-president to hold office for two consecutive terms of five years each, with an additional term after a gap of one term, BBC News explains.

A constitution implemented in 2009 created a limit of one re-election for sitting presidents, but Bolivia's Supreme Court decided that Morales' first term was exempt. This allowed him to run again in 2014. His current term ends in 2020, but if the referendum goes in his favor, the constitution could be amended to permit him to serve until 2025.

President Morales' government has been recognized for having reduced poverty in one of South America's poorest countries, by spending restructuring welfare programs and developing infrastructure, Reuters noted.

Recently, however, Morales' administration has faced criticism for corruption, financial waste, and authoritarianism. Allegations that he used his power to grant lucrative contracts to an ex-girlfriend's company appear to have shifted public opinion about the president, who maintains that the allegations are a slanderous ploy by the opposition to bring down his Movement for Socialism party, according to Agence France-Presse.

More than 29,000 polling stations have been set up throughout the country, and citizens have until 4 p.m. local time to vote. Electoral reviewers from the Union of South American Nations (UNASUR) and the Organization of American States (OAS) will be stationed in six of Bolivia's nine electoral districts to monitor the electoral proceedings, according to TeleSUR

Around 6.5 million Bolivians are expected to vote, and the government has deployed 15,000 police officers for special security during the referendum.