WASHINGTON — Owners of all but the smallest toy drones will have to register them with the U.S. government before the end of the year if the Obama administration adopts proposals being issued by a task force it appointed.

Registration – designed to make it easier for authorities to track down the growing numbers of illegal flights –should be free, easy to complete online and permit multiple devices on an owner’s filing, the task force is proposing, according to three people familiar with its recommendations who weren’t authorized to speak about it.

The recommendations will be delivered on Saturday, Federal Aviation Administration chief Michael Huerta said in a blog post Friday that didn’t disclose details.

Then comes the hard part: the FAA must find a way to adapt them to existing laws that never contemplated widespread pilotless flights. And it will have to convince skeptics that the public will comply with the law – all in time to begin registration before the Christmas holiday sales rush.

“We have a very large number of unregistered drones out there and a very unsophisticated number of operators who have no idea what the FAA requirements are – or even what the FAA does,” said Kenneth Quinn, the former chief counsel at the agency who advises drone companies as a lawyer at Pillsbury Winthrop Shaw Pittman in Washington. “To expect widespread compliance any time soon is highly unrealistic.”

Transportation Secretary Anthony Foxx called for drone registration last month to help stem growing cases of drones flying near airliners and other aircraft. The FAA has been receiving more than 100 reports a month of pilot sightings and other drone safety incidents.

Foxx and the FAA appointed the task force of 26 people representing drone manufacturers, retailers and aviation to recommend how registration would work. The FAA declined to comment beyond Huerta’s blog. The agency hopes to put rules in place before the end of the year, but may accept public input and alter the regulations later on, Huerta said.

The task force members, some of whom are still uneasy about elements of the compromise, agreed to include anything weighing more than 9 ounces in the registration program, according to the people who asked not to be named.

That’s less than one-quarter the weight of the Phantom 3, a model produced in China by the world’s largest drone manufacturer.

At the same time, the task force will recommend that online registration be as streamlined as possible. A drone owner should be able to register once for free and have it apply to multiple vehicles.

While those elements were viewed as critical to ensure that consumers would participate in registration, some may run afoul of existing U.S. law.

The FAA believes that the law requires it to charge $5 to register an aircraft.

Another daunting challenge is how the FAA will apply the complex set of existing aircraft registration rules.