WASHINGTON — Wally Backman, a popular member of the world champion 1986 Mets, will not return to the organization next season, ending a tenure marked by success on the field but constant tension off it.

Backman, 56, had spent the last seven years in the Mets’ minor-league system, the last five as manager of the club’s top affiliate, first in Buffalo and then Las Vegas.

General manager Sandy Alderson said Backman resigned to pursue big-league coaching opportunities, but sources told Newsday that the one-time Mets second baseman was fired, the product of long-standing grievances regarding his unwillingness to take direction.

“This isn’t surprising,” one official said. “He was always doing his own thing.”

Backman did not return a call for comment, but he tweeted that he resigned — another example, perhaps, of the disconnect that seemingly permeated the relationship.

“He’s decided to move on and look for other opportunities and the possibility of a major-league coaching position,” Alderson said. “We wish him well.”

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Sources described a pattern of defiance by Backman, who clashed with Alderson and others in the organization regarding matters of player development. Disagreements ranged from the distribution of playing time to lineup construction.

One recent example included the use of former first-round draft picks Gavin Cecchini and Kevin Plawecki, who often were batted at the bottom of the order. Team officials wanted them hitting higher to maximize their plate appearances.

Backman also refused to play Michael Conforto against lefties, going against the Mets’ hopes of exposing the struggling young hitter to playing time he wasn’t getting in the big leagues.

Still, the fiery Backman remained popular among his players and fans, some of whom envisioned him as a big- league managerial candidate and potential replacement for Terry Collins. Backman had been a finalist for the Mets’ top job in 2011, a post that ultimately went to Collins.

Sources said that until recently, Backman enjoyed the support of the Wilpons and also had been shielded because of his popularity among fans and his association with the franchise’s last championship team.

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“We’re very pleased with the work he did and wish him the best of luck,” Alderson said. “As I said, we had a lot of players come through there and improve and establish themselves at the major-league level.”

Backman, however, was repeatedly passed over for appointments on the major-league staff. Sources indicated that such a promotion would have been highly unlikely with the Mets.

Before the 2005 season, Backman was hired to manage the Diamondbacks, but he was fired less than a week later after revelations of legal issues that included a domestic altercation with his wife and a DUI arrest.

Backman longed to return to the big leagues as a coach, but according to a source, no other teams ever contacted the Mets for permission to interview him.