An unexpected windfall for California's education coffers has Senate Democrats pushing to dramatically expand the existing transitional kindergarten program to all 4-year-olds.

Currently, transitional kindergarten is available only to those children who turn 5 between Oct. 2 and Dec. 2. In 2014-15, the program is to expand to include those who turn 5 between Sept. 2 and Dec. 2.

That's not enough, according to Senate leader Darrell Steinberg, D-Sacramento, who along with State Superintendent of Public Instruction Tom Torlakson and Assembly Speaker John Perez, D-Los Angeles, announced plans to phase in an expansion of the existing early-kindergarten program to all 4-year-olds.

The expansion would roll out over five years, beginning in 2015-16.

Currently, approximately 120,000 children statewide are eligible for transitional kindergarten because of their birth dates. The expanded program would allow an additional 350,000 access to essentially two years of kindergarten.

"We think the research is very clear that preschool and pre-kindergarten education is invaluable to student success," said Mark Hedlund, spokesman for Steinberg.

"This is not really a new program as it is an expansion to the existing program to go full bore," he said.

"Existing transitional kindergarten only serves about 25 percent of the kids who otherwise would be eligible," he said. "The idea is to fill those gaps and have it provided to all 4-year-olds."

While some local educators expressed enthusiasm for the new plan, others said the formula has had issues in its 18 months of existence.

"One of the biggest issues is that TK never made any sense from the start," said Petaluma Superintendent Steve Bolman. "You were really creating outliers -#8212; you were providing a 14th year of education to your oldest kids. This (new plan) makes more sense than that, but (where is the) the wherewithal to pay for it when we are not spending on K-12 adequately?"

Bolman, who said research clearly shows preschool is a key component to student success, especially for students from poor families or where English is a second language, wondered whether the state K-12 system is the right home for the program.

"The research right now says that probably the most important thing we can provide to students, especially students with needs, is a preschool program," Bolman said. "Bringing it into the K-12 system, I think it's an expensive way to provide the service. Credentialed teachers are more expensive than preschool teachers."

The Senate Democrats' plan would fund the hiring of approximately 8,000 additional teachers to staff the program. The plan calls for one credentialed teacher and one qualified "associate teacher" per 20 students.

The proposal also allows for school districts and charter schools to contract with private providers who meet quality standards.

The expanded program would cost nearly $1 billion annually when fully implemented in 2020, according to estimates.

A recent report from the Legislative Analyst's Office declared there could be more than $7.7 billion in additional funding generated for schools in the upcoming fiscal year which begins July 1.

When the current transitional kindergarten was launched, there were dramatic differences in estimates of how much the program would cost.

The Legislative Analyst's Office has not been able to analyze the expense of the current transitional kindergarten because the state did not delineate between transitional and traditional kindergartners in the inaugural year of the program.

Those numbers are being collected this year, so a fiscal analysis is planned.

Initial cost figures do not include allowances for how districts will provide facilities for what could be a substantial influx of students. Many local district officials wondered aloud how to deal with potential space constraints and how to handle additional pressure on facilities and maintenance budgets that have suffered dramatic cuts since 2007.

Still, the program is a positive step for those children who need the most early support, backers said.

Calling the proposal a positive step toward some semblance of universal preschool for California's children, Santa Rosa Junior College child development instructor John Eberly said the focus needs to remain on the curriculum and who will deliver it.

"I think we need to think about what we are doing with the children when we have them there," he said.

Under the current plan, districts have significant freedom in how they teach transitional kindergartners. But in some smaller districts where only only one or two children currently qualify for the program because of their birthdays, transitional and traditional kindergartners are taught in the same classroom by the same teacher.

Expanding the program would dramatically reduce the number of combination transitional and traditional kindergarten classes that now exist. It would also provide equity by opening the program to all 4-year-olds, backers said.

"Conceptually, I think it's a great idea," Eberly said. "I think there are a lot of details to be worked out."

In the Roseland School District, where the district's Apples - Bananas Preschool has a waiting list that tops 50 students annually, the expansion news was met with enthusiasm.

"Many of our parents can't afford a private preschool tuition," Superintendent Gail Andrade Ahlas said. "About one-third of our students enter school for the first time at or around 5 years old. I would say that half of the students who are entering at or around 5 years old are learning a second language and are significantly behind with their language skills."

(Staff Writer Kerry Benefield writes an education blog at extracredit.blogs.pressdemocrat.com. She can be reached at 526-8671, kerry.benefield@press democrat.com or on Twitter @benefield.)