Although the fate of California's transitional kindergarten law is still up in the air, early-education advocates won another incremental legislative victory Thursday.

The State Senate Budget and Fiscal Review subcommittee rejected Gov. Jerry Brown's proposal to lift a requirement that school districts offer a new grade level to some 4-year-olds this fall.

Last month, the Assembly subcommittee on education finance also rejected it.

"To us, it's a very strong signal that the Senate is making," said Scott Moore, a senior policy adviser for Preschool California. "By rejecting that out of hand, it just raises the bar incredibly high for the governor to be successful in his proposal."

Concerns about children entering kindergarten too young prompted legislators to gradually roll the 5-year-old birthday cutoff date from Dec. 2 to Sept. 1. Along with the change, the law required districts to offer a two-year kindergarten program to children who turn 5 between those dates. The cutoff rolls to Nov. 1 this year, Oct. 1 in 2013 and Sept. 1 in 2014.

In January, Brown proposed eliminating the mandate. Districts would have the per-student funding to offer a transitional kindergarten program under his proposal, but they would no longer be required to do so.

Many districts, including Oakland Unified, are proceeding with plans for the new grade level, regardless of whether the law remains intact.

Brown releases a revised budget proposal in mid- May, after which the Legislature continues its deliberations.

Read Katy Murphy's Oakland schools blog at www.IBAbuzz.com/education. Follow her at Twitter.com/katymurphy.