Arlington County is in the midst of an affordable housing crisis, a sweeping demographic change that has wiped away more than half of affordable housing units for the poorest residents in the last decade according to a recent report. But advocates for preserving affordable housing are divided about what to do about it.

On one side are members of the Green Party, who have long pushed for a ballot initiative that would create a housing authority for Arlington County. On the other side are members of the Alliance for Housing Solutions, who say the authority would create a new bureaucracy that would distract time and attention from ongoing efforts to preserve affordable housing.

At the center of the debate are voters, who will have the final say next month when they head to the polls.

The debate over affordable housing in Arlington is nothing new, and county leaders have long struggled with how to cope with market demands for housing close to Washington, D.C. Opponents of a housing authority say Arlington has created more affordable housing units per capital than any other county in Northern Virginia, including those with housing authorities. Supporters are not persuaded by that argument.

"Affordable to whom?" asked Audrey Clement, Green Party candidate for Arlington County Board. "Donald Trump?"

ACCORDING TO A preliminary data report of the Affordable Housing Study, the average rent increased 47 percent in the last decade while the average salary increased only 37 percent. For lower income employment sectors, average salaries have not kept pace with increase in average rents. Meanwhile, a Virginia Tech Center for Housing Research study found that the demand for affordable housing units in Arlington is currently at 14,000. Nevertheless, opponents say, the county is doing a better job than its neighbors who are saddled with outdated housing authorities.

"The federal government is moving away from the model of the housing authority and more toward a public-private partnership approach," said Mary Rouleau, executive director of Alliance for Housing Solutions. "So if there's no new money on the table, the conversation shifts to an argument about which approach is more efficient."

Supporters of the housing authority say Fairfax County has done a better job of preserving affordable housing in part because it has a housing authority. And if the Arlington model is so successful, they argue, why has the county lost two thirds of its affordable housing since 2000? Although opponents acknowledge the county has lost market-rate affordable housing units, they say the county has been successful in setting aside dedicated units of affordable housing.

"Arlington has long used an innovative public, private and nonprofit partnership approach to the creation and management of affordable housing in our community," said Mary Margaret Whipple, former state senator and president of the Alliance for Housing Solutions. "This successful approach has allowed Arlington to access financial tools and state and federal funding in order to create mixed-income communities, while avoiding the costs of running a housing authority."

IN THE LAST DECADE, according to a recent county government report, Arlington has lost more than half of its inventory of units that are affordable for those who earn up to 60 percent of the average median income. Meanwhile, the number of committed affordable units has grown, as has the inventory of market rate units affordable to those making 80 percent of the average median income. County officials say the main reason for the loss of affordable units is increases in rent, which account for 43 percent of the losses.

"Average apartment rents in Arlington have steadily increased over the past 10 years and have tracked fairly closely to average salaries with the exception of the change from 2011 to 2012," according to the recently released preliminary data report of the Affordable Housing Study. "In 2012, the average rent jumped 13 percent outpacing salary growth."

The numbers paint an alarming picture for those who are concerned about preserving affordable housing. But opinions are sharply divided about what to do about it. Supporters of the housing authority say Arlington recently lost out on federal money that was available at the beginning of the Obama administration because it did not have a housing authority to receive the money.

"When the stimulus money became available, housing authorities had those funds available but Arlington didn't," said Stephen Davis, chairman of the Arlington Green Party. "We didn't have the hunting license we needed to apply for that money because we didn't have a housing authority."

Opponents say that they don't expect federal money to be available anytime soon. And if it does become available, they say, the county will adjust accordingly.

"If there is new money, we'll cross that bridge when we come to it," said Rouleau.