Testimony came before a legislative panel studying a proposed constitutional amendment that would force lawmakers to set aside the extra school funding each year. Directors of the departments of transportation, human services, public safety and other agencies said the plan would require devastating budget cuts.

Hundreds of mentally ill residents would go untreated, as many as 8,400 convicted felons could be freed and $400 million in highway projects would get canceled, they said.

"The scenarios described today cannot happen," said Rep. Jeff Hickman, R-Dacoma, a member of the House Appropriations and Budget Committee.

The panel is reviewing the Helping Oklahoma Public Education initiative petition. If approved by voters, it would require the state meet the regional average for per-student spending by public schools over a three-year period.

"A lot of times there are unintended consequences with legislation," said Rep. Ken Miller, R-Edmond, the committee's chairman. Miller said state agencies should be "prepared for dire consequences" if voters approve the measure in the November 2010 election.

The measure could cut other state agencies' budgets by more than 20 percent, officials said. Lawmakers have said its passage could lead to tax increases, though no statewide tax initiatives have been approved in Oklahoma in almost 20 years.

"If the question were worded, 'Do you want taxes to go up to pay for this,' it would not pass," Miller said.

The measure is supported by the Oklahoma Education Association, the state's largest teacher's group. Joel Robison, OEA associate executive director, said state agencies' predictions amounted to "a doomsday scenario."

His group claims that the money needed to pay for the additional education spending would be generated by normal growth in the state's economy and tax revenue.

Miller said the economy is predicted to remain flat for the next few years and any growth will be negated by inflation.

Figures distributed by the OEA indicate per-pupil spending in Oklahoma is $7,615 a year, the lowest in a seven-state region. The region includes Arkansas, which spends $9,591 per year; Kansas, which spends $9,544; and Texas, which spends $7,978.

The regional average for per-pupil spending is $9,078, and the national average is $9,963.

State agency heads said their departments' legislative appropriations also are below regional averages.

Transportation Secretary Gary Ridley, whose agency spends $11,540 per lane mile a year to maintain roads and bridges, said it would take "a pretty good chunk of change" to get the agency up to the regional average of $19,427.

Terri White, secretary of health and commissioner of the Department of Mental Health and Substance Abuse Services, said her agency ranks 46th in the nation in per capita spending on mental health services. She said the agency has already absorbed monthly budget cuts of $810,000 due to a statewide revenue shortfall.

"We already have too many Oklahomans going without services," White said. "We're getting close to the end of our rope."