As Memorial Day approaches, the Cape and Islands should be gearing up for high season — rentals, guesthouses, hotels, restaurants, and retail. But instead, some businesses are idling or gearing down. The reason: a faltering visa program for foreign guest workers that could end up costing these businesses dearly.

The long-running program, called H-2B, is not like the controversial H-1B visa for tech industry and other specialized-skill workers, in that it is strictly seasonal and limited to specific jobs. Also unlike H-1B, it is not a path to a green card, permanent-resident status, or citizenship, and cannot be used to replace American workers. In fact, the rigorous application process requires employers to demonstrate that no American workers were available to fill the job. The process is time-consuming and expensive. Employers must pay for the visas as well as transportation to the United States for the foreign workers.

“No employer really wants to go through this process,’’ says Jane Nichols Bishop, of Peak Season Workforce, a private company that guides businesses through H-2B hirings. “They do it because they have to.’’

The program has become the lifeblood of the seasonal business on the Cape as well as winter vacation destinations in New Hampshire in Vermont. The Cape, in particular, has a small year-round population of about 215,000, and is struggling to fill thousands of summer jobs in time of record-low unemployment rates and when necessary jobs like cooks, dishwashers, and hotel housecleaners are either unattractive to American workers or simply not practical given the area’s cost of living. The same holds true for off-Cape high school and college students — the former can find work closer to home, the latter are looking for jobs that have more career-path potential, and in either case students are returning to school long before the season ends.

The H-2B program has been hobbled since 2008, when the Department of Labor (in conjunction with Homeland Security) took direct charge of what had been a much simpler process handled by the states. And inevitably, the cap on the number of visas becomes part of a last-minute wrangling over the federal budget. This year, the budget passed on May 5 eliminated an exemption for returning workers, some of whom have been coming back the same jobs for as long as 20 years. The program’s unsettled state reflects political anxieties on both the left and the right about an influx of foreign workers .

But the upshot is that Cape businesses may be forced to curtail their hours, or the number of weeks they are open — in a seasonal business where two weeks can be the difference between profit and loss. And, of course, American workers at those businesses lose wages and jobs as well.

“There are myths that [H-2B] presents an immigration problem, there’s myths about supplanting American jobs,’’ says US Representative Bill Keating, who represents the Cape and Islands. “Indeed, it enhances local jobs here. As a result, we’re leaving revenues on the table’’ and hurting the tourism industry. . . . We’re losing revenue in our country and hurting small businesses for no reason.’’

As part of its oversight role, Congress needs to fix the H-2B program — create stable hiring caps, restore the exemption for returning workers, streamline the application process, and make sure visas are processed in a timely manner.

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