Editor’s note: A version of this article first appeared at The Guardian.

Suddenly, everyone in Washington seems to agree on the need for immigration reform, and they may even agree on most of the details. That’s because nobody has said yet what the exact details are. A “gang of eight” senators has proposed legislation, several House members have proposals, and a leaked White House immigration plan reveals that the president now has very similar designs, so it seems that agreement must be forthcoming.

But only in Washington do leaders first vote for the bill so they can later find out what’s in it. In the current immigration debate, what’s in it matters a great deal. Success or failure depends on the details.

Almost every plan for immigration reform includes enhanced border security, better employment verification, a path to some form of legal status for people already here illegally, and lastly – almost an afterthought – a new guest worker program.

As to a guest worker program … such a program cannot be an afterthought, and it cannot wait for the details to be added later. It ought to be the cornerstone of the entire effort.

A simple work-permit system can solve the problem for future workers and those already here without authorization. Such a program doesn’t need to blur the line between legal worker status and citizenship. Nor does it need to treat different groups differently, as would limited proposals like the DREAM Act, an agricultural jobs bill, or plans to grant green cards only to students with certain college degrees or those who serve in the military. Strong arguments can be made for all those approaches, but none of them solves more than a fraction of the problem, and they’re all contrary to the basic American principle of equal treatment under law. Rather, any successful program must guarantee three essential elements – opportunity, protection and fairness – for employers, for new workers coming in, for those already here illegally, and for Americans worried about border security.

Opportunity, protection, and fairness are in the eye of the beholder. That’s why so much discussion centers on a market-driven plan called the Red Card Guest Worker Permit – a quick and simple process whereby private employment firms would be authorized to set up offices anywhere in the world, run criminal background checks on prospective workers, and issue guest worker permits to specific workers for specific jobs. These firms would utilize the most modern technology, always readily employed first in the private sector, but often coming to government bureaucracies ever so slowly.

Private employment firms operate databases on which employers post available jobs and workers post qualifications, each paying their own fees for the service, which offers an already-understood process for matching foreign workers with American employers who need them. This proposal would simply allow these companies to do what they do best: match workers and jobs, and issue guest worker permits with smart-card technology that allows tracking, changing, upgrading, renewing, or cancelling as needed. That provides answers for people on both sides of the politics.

For conservatives, that means opportunity: for businesses to get the workers they need, for workers to find legal jobs and earn good money, for the economy to grow and prosper. It means protection: from mass amnesty and from a porous border. And it means fairness: in keeping families together and treating all equally – no special deals are needed for special groups. In fact, under this plan, there would be no further need for the alphabet-soup of complex visa classifications that add to the bureaucratic nightmare currently faced by employers and employees alike.

For liberals, the same program means opportunity: by giving workers upward mobility, portability, and renewal as long as they stay employed and productive. If they wish, they can apply for citizenship while working legally, a completely separate process. It means protection: against abusive employers, freedom from exploitation, and the ability for workers to enter through a gate rather than risking their lives sneaking across borders or paying exorbitant fees to smugglers and coyotes. And it means fairness: in bringing families together (both sides care about that), and equal treatment for all – a chance for the undocumented to come out of the shadows and be treated like all other workers.

Any plan that appeals to people on all sides of this debate will inevitably attract attention. This one is already being considered carefully by a wide range of policy makers and congressional leaders in both Houses. A market-based guest worker component must be part of any immigration reform that has a chance to work, but it is more than just one part – it is the cornerstone.

Helen E. Krieble is founder and president of The Vernon K. Krieble Foundation, author of “Two Paths to Safety: A Private Sector Initiative to Break the Illegal Immigration Deadlock.,” and a contributing scholar with The Center for Vision & Values at Grove City College.