By MANUEL ERNESTO RIVERA, Associated Press Writer

Puerto Ricans voted to do away with half their lawmakers, endorsing a one-house legislature that supporters say would be cheaper and more efficient.

Final results from Sunday's referendum showed nearly 84 percent of voters endorsed the concept of replacing the state Senate and House of Representatives with a one-house, or unicameral, legislature.

Turnout was about 22 percent, extremely low by Puerto Rican standards. Still, Gov. Anibal Acevedo Vila said the results show that voters seek a "profound reform."

"The democracy that we love and defend demands that we take immediate action to respect the will expressed at the ballot box," said Acevedo, who backed the switch to a unicameral system.

The results won't bring about immediate change: The referendum directs the legislature to hold another referendum in 2007 that would ask voters to amend the island's constitution and establish a one-house system by 2009.

Opponents of the change suggested the results may not be binding on lawmakers.

"If the electorate ignored this process, the legislature also should ignore it," said Thomas Rivera Schatz, secretary-general of the pro-statehood New Progressive Party, which controls both the Senate and House.

Adolfo Krans, a businessman and a leader of the pro-unicameral movement, said the results were a strong mandate for change, and would compel the legislature to set the second vote.

"They are going to try to run away from it, but they are going to find themselves up against a wall because even though 80 percent didn't vote, there are many people who want a unicameral system," Krans said.

Those who favor the unicameral system say eliminating either the Senate or the House — which one hasn't been decided — would be more efficient and would reduce some of the political infighting that has dominated the political scene in recent months.

Opponents say the change would create a system that would be less open and democratic, with fewer checks and balances on the political process.

Only one U.S. state, Nebraska, has adopted the unicameral system.

Senate President Kenneth McClintock and the leader of the House of Representatives, Jose Aponte, said Sunday they would follow the results of the referendum though both had previously said they weren't obligated to do so unless it was an overwhelming mandate.

The Legislative Assembly has existed since the 1952 constitution that established the island's status as a U.S. commonwealth. It has a 27-member Senate and a 51-member House of Representatives.

Puerto Rico's 4 million people are U.S. citizens and can be drafted into the military but cannot vote for president and have no voting representation in Congress. They also pay no federal taxes.