By Dave Boucher, USA TODAY NETWORK - Tennessee

More than $750,000 buys plenty of campaign mailers and advertisements. But it doesn't necessarily buy election wins.

Stand For Children, an education advocacy organization, found that out the hard way Thursday night. After spending a small fortune, all four candidates it backed in the Metro Nashville school board election and a handful of state GOP primary challengers lost their races.

"I think Nashville has become a model of how you defeat an obscene amount of dark money in local school board elections. At the end of the day, there's a certain sanctity between public school parents and their locally elected school board. And it's not for sale to the highest bidder," said Jamie Hollin, a former Metro councilman and political operative.

Noting he's a proud public school parent, Hollin added, "I am particularly proud to put the nail in the coffin of the charter school movement in Nashville."

Stand for Children, which advocates for charter schools as well as prekindergarten programming and other education issues, financially supported 10 school board or statehouse candidates in the primary, specifically spending more than $200,000 on school board races. Only one who faced an incumbent won: Sam Whitson easily defeated embattled Rep. Jeremy Durham, who had suspended his re-election campaign after an attorney general investigation detailed allegations of inappropriate sexual conduct by Durham against 22 women.

Metro school board incumbents Will Pinkston, Amy Frogge and Jill Speering defeated their Stand for Children-backed opponents, Jackson Miller, Thom Druffel and Jane Grimes Meneely, respectively. Only the Pinkston-Miller race was close, with Pinkston winning by 36 votes. Miranda Christy, the Stand for Children-supported candidate in the race to replace retiring board member Elisa Kim, lost by more than 30 percentage points to newcomer Christina Buggs.

Dan O'Donnell, the Nashville director at Stand for Children, said it's always difficult to take on incumbents. He said each of the candidates supported by Stand for Children ran respectful campaigns his organization was proud to support.

"At Stand, we believed new leadership was of the utmost importance to improving outcomes for students, and we devoted enormous time, energy, and resources to electing that new leadership. But no one's support could match the heart and soul that these candidates, their families and supporters poured into these races," O'Donnell said in an emailed statement.

"Now the campaigns are over, and we are committed to finding common ground. We should work together to support (Metro Director of Schools) Shawn Joseph's vision, ensure that there is a high-quality school in every neighborhood, and ensure that schools and families have the resources they need from pre-K through graduation. We should all work toward the same goal: a high-quality education for every child in Nashville."

Metro Councilman Jeremy Elrod, who represents part of Pinkston's district, agreed with Hollin that Thursday's results are a resounding rebuke of the spread of charter schools. "Nashville can decide for itself how it wants to move forward with education, and that we aren't going to be bought by outside special interest groups," Elrod said.

In addition to Durham at the statehouse level, Stand for Children took on sitting Republicans who are on the far right of the political spectrum.

Rep. Courtney Rogers defeated Stand candidate Beth Cox 55 percent to 44 percent.

Rep. Judd Matheny defeated Will Lockhart 59 to 32 percent, with a third candidate getting 9 percent.

In the race for the seat vacated last year by Rep. Leigh Wilburn, Stand's candidate Ron Gant won a three-way primary with 68 percent of the vote.

Stand candidate Christy Sigler came in third of four candidates vying for the GOP primary race to replace retiring Rep. Rick Womick.

As of late Thursday night, Stand candidate Chad Keen, who was recently appointed mayor of Bristol, was down 47 votes in the race to replace Rep. Jon Lundberg, who won his state Senate GOP primary.