Slidell Police Chief Randy Smith was elected sheriff of St. Tammany Parish on Saturday, narrowly denying Jack Strain a sixth term in an upset that saw yet another longtime north shore incumbent forced from office.

Smith led the sheriff all night, beginning with the early voting ballots, and ended up capturing 52 percent of the vote.

“From the beginning, our campaign has felt incredible momentum,” Smith told supporters Saturday night. “Challenging an entrenched incumbent took courage, not just for me but for the thousands of supporters who were ready for a change. We’re obviously ecstatic at this outcome and look forward to the transition leading up to the oath of office on July 1.”

Smith did not indicate when he will resign his current job, which will clear the way for the City Council to call a special election to choose his replacement.

Early in the runoff, Smith sought to assure the 750 employees of the Sheriff’s Office that he doesn’t plan to clean house. Sheriff’s Office employees do not have civil service protection and serve at will.

He posted a letter on his Facebook page addressing concerns. “The rumor that I will be ‘firing everyone’ is absolutely absurd,” he wrote, saying that the days of “fear tactics” are over. Smith did say that there are some “leadership issues” within the agency and that “those issues and individuals” would be addressed on a case-by-case basis.

Smith had run second in the Oct. 24 primary, winning 37 percent of the vote to Strain’s 45 percent. The popular police chief, who was elected to a second term without opposition in 2013, ran strong in his home base, eastern St. Tammany Parish. Strain, who hails from Abita Springs, had a geographic advantage in the west, and had also received the support of the third-place finisher, retired U.S. Customs agent Scott Illing, who is also from the parish’s western side.

Strain had a larger campaign chest and in the final week of the campaign had picked up the endorsement of Parish President Pat Brister, who was re-elected easily in October.

But in the end, Strain’s advantages were not enough to put him back in office. Smith, who announced his candidacy in January, ran a tough race that sought to capitalize on voter discontent with long-term incumbents and high-profile corruption cases.

Had he won, Strain would have been the only parishwide official in recent memory to survive into a sixth term. Clerk of Court Malise Prieto, who is serving her fifth term, decided not to seek another, citing a toxic political atmosphere.

Walter Reed also decided not to run for a sixth term as district attorney as the pall cast by a federal investigation targeting him deepened. He was indicted in April. Another longtime incumbent, Coroner Peter Galvan, resigned in 2013 before pleading guilty to corruption charges.

Strain was clearly viewed as vulnerable. Candidates who ran as outsiders were victorious in recent races for parishwide office: Chuck Preston, who was elected coroner, and Warren Montgomery, who was elected district attorney nearly a year ago. Montgomery was in a runoff with Brian Trainor, Strain’s chief deputy, and the sheriff had backed Trainor strongly in the race. His loss was seen by some as a rebuke to Strain.

Against that backdrop, three candidates qualified to run against Strain, who had not faced a challenger in a dozen years.

All three of Strain’s opponents tried to capitalize on growing voter antipathy toward establishment candidates. But the primary was low-key compared to the runoff. Smith hammered on the theme that St. Tammany has been embarrassed by corruption, and suggested that Strain was part of the problem. One TV commercial featured a speaker addressing Strain, saying, “Politicians like you keep getting arrested for stealing money from taxpayers.”

Smith also pointed to a work-release program run by Strain’s campaign treasurer that was dogged by controversy. Strain shut it down in 2014 after a rash of escapes.

Among other things, Smith’s platform included a promise to establish a corruption unit to work with state and federal officials in rooting out wrongdoing.

The sheriff’s campaign script mainly stressed his role in keeping St. Tammany Parish safe. He took shots at Smith, sending out a mailer that unfavorably compared Slidell’s crime rate to that of the parish. He also took a stab at tying Smith to political scandals, with mailers that highlighted a contract between Galvan and Slidell’s jail. “Stop the embarrassment of corruption,” one mailer said. “Say no to Randy Smith.”

But voters said yes, and Smith overcame a sheriff who had once seemed unassailable.

Follow Sara Pagones on Twitter, @spagonesadvocat.