Majority Leader Trent Lott offered a mild endorsement Wednesday of the White House-backed education bill making its way through Senate, but said spending levels have "exploded totally out of control" and must be reduced.

Lott, R-Miss., also expressed concern about efforts to lessen flexibility the bill offers to school districts in their use of federal funds. But overall, he said, "I still think there's enough in here worth having."

Lott made his comments to reporters as Democrats offered the latest in a series of politically attractive amendments to raise recommended spending levels in the measure.

A proposal by Sen. Barbara Boxer of California to increase funds for after-school programs won approval, 60-39.

But an amendment by Iowa Sen. Tom Harkin to add $1.6 billion for school construction and modernization failed on a near-party-line vote of 50-49.

Republican aides, speaking on condition of anonymity, said the rejection of the school construction amendment was important in the effort to solidify shaky support among GOP lawmakers.

By a Democratic tally, a series of amendments adopted on the Senate floor thus far has raised recommended spending by more than $9 billion for next year over Bush's proposals.

That has led to conservative grumbling about the measure, and Lott's comments reflected that concern.

"The biggest problem in the Senate bill is just the authorization levels have exploded totally out of control," Lott said, referring to amendments that called for additional spending on teacher training, disadvantaged students, disabled students and other programs.

Lott said he was convinced that "more reasonable" levels would emerge from House-Senate compromise negotiations later this year.

Addressing the subject of flexibility, Lott said, "It is important that the reforms stay in there as they are."

The overall bill is designed to improve student performance. Schools would be given somewhat greater flexibility in their use of federal funds, and some states and local school districts would have considerably more leeway.

The bill also requires annual reading and math testing of students in grades three through eight.

Schools judged to be failing based on the student test scores would receive additional assistance. Some students would be permitted to use federal funds to pay for tutoring or transportation to another public school.

Lott spoke as House GOP leaders prepared for Thursday's opening of debate on a companion education measure. The bill emerged from committee with strong bipartisan support, but supporters must navigate a series of amendments on the House floor that threaten to unravel their coalition.

Conservative Republicans are making an effort to give states and school districts greater flexibility in their use of federal funds. But Rep. George Miller, D-Calif., the senior Democrat on the House Education and the Workforce Committee, said that if that happens, "It's the end of the bipartisan coalition."