For years, receiving a Section 8 housing voucher was a golden “ticket to stability” for some of Portland’s neediest.

But in recent months, Portland’s increasingly tight rental housing market has disrupted the path out of homeless shelters or transitional housing for poor adults, families and the disabled.

The lack of available housing means stiffer competition for available apartments, higher rental rates for open units and more stringent requirements to move in, according to Portland housing officials, landlords and people who work with voucher recipients. And because some people who were provided Section 8 vouchers have not been able to find apartments, the agency that distributes vouchers in Portland could see a reduction in federal funding for next year.

“This is as tight as I’ve seen it,” said Mark Adelson, executive director of the Portland Housing Authority. “We have people who have been out there a long time looking. There’s just not a lot of housing out there.”

In 2012, the average time between an individual receiving a voucher and finding housing was 49 days. This year it has spiked to 70 days, and in some extreme cases has stretched to over 100 days. The increased waiting means that only about 50 of the agency’s available 100 vouchers will be used this year.

Typically, voucher recipients have 60 days to find housing; failing that, most can request an extension for an additional 60 days. If voucher recipients cannot find an apartment in time, they lose their voucher and must wait months for a new application to be processed. The situation not only leaves people without housing, but could begin to have financial repercussions for the housing authority.

The federal government gives the housing authority about $1.5 million to administer 120 vouchers, contingent on recipients either finding a place to live or continuing to actively look for housing.

But this year the agency is expected to issue 20 fewer vouchers, despite having a waiting list for people seeking assistance, potentially jeopardizing part of the housing authority’s administrative grant.

“We don’t know what that (funding cut) is going to be yet,” Adelson said.

He said the people who have the hardest time finding housing are the disabled seeking one-bedroom apartments, and families requiring multiple bedrooms. (There is no time limit for disabled voucher-holders, Adelson said.)

To meet demand, the housing authority has been forced to place people in outlying towns, sometimes as far away as Old Orchard Beach or Freeport, where they are far from the services, job opportunities and public transportation networks they’re accustomed to inside Portland city limits.

Anecdotally, the hot rental market has given landlords the luxury of selectivity, Adelson and others have said. Some landlords can demand nonrefundable application fees and additional months of rent paid upfront. Others choose to increase rent above what a voucher will cover. Some simply choose not to participate in the voucher program altogether.

“I don’t have any evidence to support that,” said Adelson, who has been with the Portland Housing Authority for 10 years. “But that can happen when times are good. When times are bad, we have landlords on our doorstep.”

Like any complex economy, the housing market in Portland is the product of many coexisting forces that push and pull demand and prices for different reasons.

Portland’s rise as a comfortable, desirable place to live has meant that a unit in acceptable condition can typically be rented at market rate.

While the vacancy rate in the city hovered last year around 2 percent to 3 percent – meaning there were two or three vacancies for each 100 units – the recent vacancy rate has been “effectively zero,” said Brit Vitalius, president of the Southern Maine Landlord Association, citing a survey conducted by his group.

Typically, rents have increased about 5 percent annually over the past eight years. This year’s average increase has exceeded that rate, he said.

“There was a time when vouchers paid more than the market,” Vitalius said. “The rents are going up so fast now, the vouchers can’t keep up.”

Donna Yellen, a social worker and chief program officer at the Preble Street Resource Center, said the result has been frustration and demoralization for people who believed that a voucher was a path to a better life.

Yellen said a few recent trends in the market have resulted in fewer available full-time rental units.

The arrival of sharing-economy websites such as Airbnb, which pairs people who have open rooms or apartments with customers who will pay to stay there short term, have taken units off line that could have gone to people looking for year-round homes.

The other factor has been a recent push toward seasonal renting. Landlords renting to tourists in the summer at vacation-home prices can make as much as they do from a yearlong lease.

Cassie Irish, 36, was granted a voucher for $812 a month, but lost it in November after she could not find a place that would accept her as a tenant. Landlords wanted references and proof of income, and sometimes, nonrefundable application fees, none of which she could provide.

She sees an apartment as a keystone to ending her two-year spate of homelessness.

Without a place to stay, she struggles to control her anxiety and depression, making it difficult for her to apply for or keep a job. So when landlords ask for a work history, she feels like she’s going in circles.

“Its a Catch-22,” Irish said. “Right now I can work (and) I’m trying to get myself put back together to the point where I can get a job, but its really hard when I don’t know where I’ll be staying. If I had a place, I wouldn’t have half the problems I have right now.”