The National Highway Traffic Safety Administration's seat-belt "education program," never a popular item among lawmakers, has run into still more trouble on Capitol Hill.

NHTSA is seeking $80 million over the next four years to, as agency administrator Diane K. Steed puts it, "provide those people who shape public opinion on safety and health issues . . . with current factual information about safety belts and other forms of occupant protection, and to enlist their assistance in communicating this information to the public at large."

The problem, some legislators say, is that those "other forms of occupant protection" -- namely, air bags, automatic seat belts and cars with so-called "friendly" interiors -- seem to be getting short shrift in NHTSA's efforts. As a result, some members are trying to tighten the strings of the purse holding NHTSA's seat-belt money.

NHTSA has received only $2.5 million of the $20 million it has requested for fiscal 1985. The agency recently asked Congress to release $10 million more this year. But the House Appropriations subcommittee on transportation, which oversees NHTSA's budget, agreed to give the agency another $5.25 million.

The agreement, however, was loaded with stipulations. Chief among those was that NHTSA must use $3.5 million of the $7.25 million total "to overcome the misinformation and lack of knowledge that now exist regarding automatic belts and air bags, and to encourage public acceptance of these devices."

The subcommittee allocated $4.25 million "for general safety belt education, information and enforcement activities with special emphasis on efforts in those states that have passsed belt use laws."

The stipulations were included in an April 3 letter from subcommittee Chairman William Lehman (D-Fla.) to Transportation Secretary Elizabeth Hanford Dole.

"We do not intend to proceed with additional funding" for the seat-belt program "until we are provided with information demonstrating the effectiveness of the activities funded at the $7.75 million level," Lehman said in the letter. The Senate Appropriations subcommittee on transportation is reported close to approving a similar approach to NHTSA's seat-belt funding requests.

Underlying the lawmakers' skepticism is their belief that DOT yielded to the automobile industry last July 11 when the department published its "final" regulation on automatic crash protection, or so-called passive restraint devices.

Under the rule, all auto makers doing business in the United States must equip all new cars with passive restraint systems by April 1989, unless states with two-thirds of the nation's population enact mandatory seat-belt laws by then. As a result, most of the nation's auto makers have been lobbying state legislatures to pass such laws. So far six states -- New York, New Jersey, Michigan, Missouri, Illinois and New Mexico -- have put seat-belt laws on the books.

But Lehman and other Capitol Hill lawmakers are not convinced that those laws are strong enough to improve highway safety. They are also asking NHTSA and DOT to answer many questions about the efficacy of the state statutes before more money is spent on seat-belt "education programs."

DOT and NHTSA officials have long contended that they are not pushing seat belts at the expense of passive restraints. At this writing, however, neither DOT nor NHTSA has responded officially to Lehman's letter.