The union that represents the deputies who responded to the Florida high school massacre is holding a no-confidence vote on the sheriff, with the labor group's leaders saying he should have accepted some blame for the shooting.

The Broward Sheriff's Office Deputies Association is conducting a poll of its members about their confidence in Sheriff Scott Israel, who strongly denounced the vote as a union tactic to get pay raises. The electronic poll ends Thursday night.

President Jeff Bell said Friday that Israel's handling of the Marjory Stoneman Douglas High shooting that killed 14 students and three staff members is a major component of the no-confidence campaign, saying he should not have put the full blame on Deputy Scot Peterson, the school's resource officer.

Video shows Peterson remained outside after investigators say former student Nikolas Cruz opened fire Feb. 14 inside the three-story freshman building with an AR-15 semi-automatic rifle. Israel said shortly after the shooting that Peterson should have rushed into the building to confront and kill Cruz. Peterson retired rather than accept an unpaid suspension.

Bell also has criticized Peterson, but said Israel should not have publicly singled the deputy and should have placed him on paid leave until an investigation into his conduct was completed. He said only deputies accused of crimes are placed on unpaid leave and Peterson has never been charged.

Israel issued a statement Friday saying it is “unfortunate and appalling” that Bell is using the school shooting “as a bargaining tactic to extort a 6.5 percent pay raise” for the union's members. The 3-year-old union represents the office's deputies who hold the rank of sergeant and below, and its contract expires Sept. 30.

Shortly after the shooting, Israel faced backlash for his agency's possible mishandling of some of the 18 tipster calls it had received about Cruz, 19. The tips were among a series of what authorities now describe as the clearest missed signals that Cruz, who had a history of disturbing behavior, posed a serious threat. Israel praised himself in a TV interview shortly after the shooting, saying he had shown “amazing leadership” in the tragedy's wake.

Bell said contract negotiations played no role in calling the vote and there are other issues besides the shooting. Bell said he discovered the administration had authorized a local auto parts store that supplies the agency's repair shop to fill its trucks at the office's pumps, taking thousands of dollars of taxpayer-funded gas. Also, he said Israel says the office cannot afford new guns, equipment and training for deputies but the agency underspent its budget by $100 million last year and is on pace to do it again this year.

“We just want the equipment and training needed to keep the community safe,” Bell said.

Israel, a Democrat, was overwhelmingly re-elected to a second term in 2016. Republican Gov. Rick Scott rejected calls from some state legislators to suspend him after the shooting.

Cruz's lawyers have conceded he is the shooter and say he will plead guilty in exchange for a life sentence. Prosecutors say they will seek the death penalty.

Terry Spencer reports for the Associated Press.