Even the best initiative in the world can't do any good if no one knows about it. That, apparently, is the thinking of Obamacare's opponents. They have begun aiming their attacks on navigators, the people whose job it is to inform the public about how to gain coverage through the new insurance exchanges.

The Florida Department of Health issued an order this week that prohibits navigators from advising uninsured residents on the grounds of the state's 60 local health departments. That will make it more difficult to reach those who need the law's benefits the most.

In at least 16 states, laws have been passed or are under consideration to subject navigators to new layers of regulation. The Georgia insurance commissioner has declared that he will require navigators to pass the same licensing test as insurance brokers, even though their role is different.

And House Republicans have used an investigation into the role of navigators to demand that 51 community groups that serve as navigators answer voluminous inquiries into their activities. Many of these are small nonprofits with limited resources. Several have said the demand could seriously interfere with their work.

The Obama administration last week told the groups they do not have to respond to the inquiries, but it is not clear whether the investigators will continue to pursue their demand.

The role of navigators is particularly important because as late as last June, a majority of uninsured Americans had not even heard of the new insurance exchanges through which they can obtain coverage. These personal guides form an important resource in finding affordable policies.

What reasons do Obamacare opponents give for their efforts to impede the work of navigators? The Florida Department of Health cited privacy concerns, although they declined to explain why navigators pose a greater threat than any other government program, including Medicare. Congressional Republicans cited the $67 million cost of the navigator program as the reason for their investigation. But that amount is miniscule compared to the cost of most government activities, including Congressional investigations.

The only plausible explanation for these efforts is that they are an attempt to prevent navigators from doing their job. That would keep millions of uninsured Americans in the dark about the law. They would not know that health insurance, which was denied them before, is now available. And that means they would continue to be kept from getting care that could improve their health or even save their life.

We should be thankful that such efforts were not used in the past. Hostility to the passage of Medicare in 1965 was intense, but opponents made no attempt to conceal the program from its beneficiaries. If they had, millions of elderly Americans might never have received the needed care to which they were entitled.

If opponents believe that Obamacare is destined to fail, why do they need to put obstacles in its way? They could prove their point by standing aside and letting it play out on its own. They will have proven nothing if the law fails because they were able to undermine it.

In the meantime, those who stand to lose the most are not the thousands of people in nonprofit organizations working to make it succeed. They are the millions of uninsured Americans who won't even know that they had the chance to get the health care they need, but that it was taken away.

Robert I. Field is the author of Mother of Invention: How the Government Created 'Free-Market' Health Care, just released by Oxford University Press.