The accusation was made last week by an investigator with Congress’ Government Accountability Office, which highlights the DTV concern in a report to be released in November that could further fuel the controversy surrounding the changeover.

NTIA Chief John Kneuer said a single government entity dictating public educational efforts would dissuade industry groups from voluntarily running public-service advertisements. "Each of these industries has their own incentives, has their own messages," he said Tuesday.

The regulators spoke at an NTIA meeting designed to promote the shift from analog to digital signals. But the forum exposed some potential shortcomings, including the fact that industry stakeholders coordinating educational efforts have not produced TV ads explicitly mentioning a $1.5 billion coupon program being implemented by NTIA.

The vouchers will reduce the cost of converter boxes that tens of millions of Americans relying on over-the-air reception will need for analog sets to work after the Feb. 17, 2009 switchover.

TV spots created by the National Cable and Telecommunications Association and National Association of Broadcasters refer viewers to Web sites or telephone numbers but do not discuss the vouchers, which citizens can begin requesting Jan. 1.

"Yes, we'll have ads that will talk about the converter-box program and coupons," NAB President David Rehr said during a question-and-answer session. But he was not sure when, saying they "probably" would air by January.

Kneuer later insisted that given the collaborative efforts underway, awareness about the coupons and the transition would be "overwhelming."

During his speech, Martin said the FCC's "highest priority" is to protect American consumers. But speaking to reporters, he balked at additional public-interest obligations for digital broadcasters. Martin emphasized, however, that the FCC previously mandated extra children's programming requirements.

"I think that we've taken a significant number of steps in that regard already," he said.

FCC Commissioner Jonathan Adelstein, a Democrat and frequent critic of the transition's progress, said there is still time to get things right but reiterated his warning about a "tsunami of complaints" if serious problems arise.

Rep. Fred Upton of Michigan, the senior Republican on the House Energy and Commerce Telecommunications and the Internet Subcommittee, sided with broadcasters in their opposition to vacant television channels being used for unlicensed, wireless, high-speed Internet access.

Upton said the "white space" should be auctioned and licensed, insisting "that is the most efficient way to allocate the spectrum and promote innovation." The approach also would prevent interference with DTV signals because license holders could be held accountable, he said.

Martin said the FCC wants to issue a decision by October but may do so behind the scenes rather than at a public meeting.