— The Senate’s 2013-14 budget could buy $15 million worth of new school buses for South Carolina’s oldest-in-the-nation fleet, as part of its $6.3 billion plan for state spending.

Senators considered an amendment Monday to their budget plan that would distribute nearly $7 million extra that lottery sales are expected to bring in the next fiscal year, according to revised revenue estimates approved last week by state economic advisers. The proposal puts $2.75 million of the higher-than-initially-estimated profits toward school buses.

A spokesman for Republican state Superintendent Mick Zais said the proposed allocation is encouraging but still falls far short.

“We have a long way to go to get the bus fleet cost-effective for taxpayers and on the schedule recommended by law,” said spokesman Jay Ragley.

New buses not only mean students are more likely to get to school on time, but they’re more fuel efficient and cheaper to maintain, Zais has said. The $15 million could buy about 200 buses.

Republican Gov. Nikki Haley continues to advocate for transferring the fleet’s responsibility to districts. Her budget recommended the state sell all of its buses and let districts either be fully responsible for running their own buses or contract for services. That idea has gone nowhere in the Legislature.

Two-thirds of the buses in South Carolina’s fleet for public schools remain at least 15 years old. That’s despite the arrival of 342 new school buses this school year that replaced models up to 28 years old.

Nearly 90 percent of those buses’ $28 million cost came from lottery funds that legislators designated during the current and last fiscal years, mostly from unclaimed lottery prizes.

It marked the state’s first significant purchase for the fleet in four years. Zais asked legislators for $46 million for school buses in 2013-14.

In 2007, legislators approved replacing the statewide fleet every 15 years, but they ignored the law for years amid the economic downturn.

Meeting the replacement recommendation would require $34 million, Ragley said.

Sen. John Scott asked his colleagues to find at least $10 million more in the budget for buses.

“We’re not scratching the surface on buying buses,” said Scott, D-Columbia.

The amendment on lottery revenues would put $1 million more toward digital textbooks for school districts, bringing the total for the new option to $4 million. It’s unclear how many districts could benefit.

State law limits the spending of lottery revenue to colleges, public libraries and certain programs in kindergarten through 12th grades, including transportation and instructional materials.