SAN JUAN, Puerto Rico >> Puerto Ricans are getting the chance to tell the U.S. Congress on Sunday which political status they believe best benefits the U.S. territory as it remains mired in a deep economic crisis that has triggered an exodus of islanders to the mainland.

Congress ultimately has to approve the outcome of Sunday’s referendum that offers voters three choices: statehood, free association/independence or the current territorial status.

Many expect statehood supporters to crowd voting centers because three of Puerto Rico’s political parties are boycotting the referendum, including the island’s main opposition party. Among those hoping Puerto Rico will become the 51st state is Pedro Pierluisi, the island’s former congressional representative.

“Let’s send a loud and clear message to the United States and the entire world,” he said in a statement today. “And that message is that we Puerto Ricans not only want our U.S. citizenship, but we want equal treatment.”

The referendum coincides with the 100th anniversary of the United States granting U.S. citizenship to Puerto Ricans, who are barred from voting in presidential elections and have one congressional representative with limited voting powers.

Many believe the island’s territorial status has contributed to its 10-year economic recession, which was largely sparked by decades of heavy borrowing and the elimination of federal tax incentives. Puerto Rico is exempt from the U.S. federal income tax, but it still pays Social Security and Medicare and local taxes but receives less federal funding than U.S. states.

Nearly half a million Puerto Ricans have moved to the U.S. mainland in the past decade to find jobs and a more affordable cost of living as the island of 3.4 million people also struggles with a 12 percent unemployment rate. Those who remain behind have been hit with new taxes and higher utility bills on an island where food is 22 percent more expensive than the U.S. mainland and public services are 64 percent more expensive.

Those who oppose statehood warn that Puerto Rico will struggle even more financially because it will be forced to pay millions of dollars in federal taxes. Many also worry the island will lose its cultural identity.

Sen. Eduardo Bhatia of the opposition Popular Democratic Party plans to boycott Sunday’s referendum.

“To not vote in a process that has not been validated by any party in Puerto Rico, or by the U.S. government or by anyone outside the New Progressive Party is to respect oneself,” he tweeted today.

A spokesman for the U.S. Justice Department told the Associated Press that the agency has not reviewed or approved the ballot’s revised language. Federal officials in April rejected the original version, in part because it did not offer the territory’s current status as an option. The administration of Gov. Ricardo Rossello added it and sent the ballot back for review, but the department said it needed more time and asked that the vote be postponed, which it wasn’t.

Sunday’s referendum is the fifth one for Puerto Rico.

No clear majority emerged in the first three referendums, with voters almost evenly divided between statehood and the status quo. During the last referendum in 2012, 54 percent said they wanted a status change. Sixty-one percent who answered a second question said they favored statehood, but nearly half a million voters left that question blank, leading many to claim the results were not legitimate.

Thousands of Puerto Ricans already cast their vote earlier this week in the newest referendum, including inmates and those who are hospitalized.