Weary of the state’s chronic underfunding of Tennessee’s largest public school district, the Shelby County School Board voted Tuesday to explore suing the state over how it funds K-12 education.

With the board’s 9-0 vote, Shelby County Schools joins a growing list of districts ready to move toward litigation against the state over the funding issue.

School boards in Knox, Hamilton and Bradley counties voted earlier this month to pursue legal discussions, and leaders of Metropolitan Nashville Public Schools are expected to consider the matter in several weeks.

At issue is the state’s Basic Education Program (BEP), the funding formula through which state education dollars are generated and distributed to Tennessee schools. The BEP is defined by the state as the amount of funds sufficient to provide a “basic level of education for Tennessee students.”

But like elected education officials in other districts, Shelby County leaders say the district has not received all the state money it’s due – exacerbating its struggle to raise teacher pay, improve test scores and provide the innovations necessary to address gaps in student learning.

Board member Chris Caldwell, who proposed the resolution to explore legal options, estimates that Shelby County Schools stands to receive at least $103 million more annually if the state pays its full obligation under the BEP.

“For the last two years, the state dangles a carrot out there that they’re going to do something,” Caldwell said. “They have not shown any proclivity or desire to fully fund education. It’s not their priority.”

Tennessee ranks 45th in the nation in per-pupil spending, according to the U.S. Census Bureau.

While school boards are organizing for a lawsuit, many district leaders hope to avoid that option by allowing the Tennessee General Assembly to address the issue this year when approving the state’s upcoming budget.

If the districts band together and sue, it won’t be the first time districts have gone to court over the state’s education funding formula.

In 1988, 77 small school systems sued the state, claiming its funding formula –  known as the Tennessee Foundation Program – was inequitable. The Tennessee Supreme Court agreed and ordered the state to develop a plan to correct the problem. In 1992 with the passage of the Education Improvement Act, Tennessee implemented the BEP, and the formula has continued to be adjusted through the years.

In 2007, the legislature rewrote the formula to take into account a county’s ability to to cover funds for public schools. However, district leaders say the state has never adequately funded the revised formula – giving them standing, they say, to file another lawsuit.

In his 2015-16 budget proposal for K-12 education, Gov. Bill Haslam proposed spending an additional $97 million toward teacher raises and another $44 million for local schools under the BEP.