WASHINGTON (AP) — A long-simmering dispute between Washington's Metro administration and its largest union has publicly escalated into threats of a strike just as thousands of tourists arrive in the nation's capital for Tuesday's Major League Baseball All-Star Game.

Members of the Amalgamated Transit Union Local 689, which represents around 8,000 of Metro's 12,500 active workers, overwhelmingly voted Sunday evening to authorize a strike. The vote opened up the possibility that Metro workers could stage some sort of work stoppage or slowdown during the All-Star Game or Monday night's home run contest.

"The timing is definitely not a coincidence," said Washington Councilmember Jack Evans, who serves as chairman of the Metro board. "I hope cooler heads prevail."

Striking is forbidden under Metro's bargaining agreement with the union, but even a brief interruption could cause commuting chaos, particularly as thousands of visitors try to get to the All-Star game events. The transit system carries about 1 million people a day and any shutdown would also potentially hinder the functioning of the federal government.

A union statement Monday gave no indication of when or if an actual strike would be considered, and blamed the current impasse on Metro General Manager Paul Wiedefeld — accusing him of "blaming his workers for the incompetence of him and his team."

Union members have been working without a contract since July 2016, with negotiations stalling over salaries, job cuts and the privatization of certain jobs. Binding arbitration of the dispute was ordered last fall but both sides are still awaiting the arbitrator's ruling.

The board of the Washington Metro Area Transit Authority issued a response Monday afternoon, saying that the transit network faces chronic funding problems that must be addressed.

"We must find solutions together by continuing to talk and listen," the statement said. "The collective bargaining process is the appropriate and legal path to finding solutions."

Because Metro workers are forbidden from striking under the system's governing compact, a judge or arbitrator could order an end to any strike and penalize those who do not comply.

As negotiations have dragged on with little sign of progress, the union has escalated its rhetoric and tactics. Twice in July, union workers have staged coordinated "late out" protests, with employees disrupting train and bus service by coming in late for their scheduled shifts.

Evans defended Wiedefeld's performance, saying he "has to cut expenses and 80 percent of our expenses are in labor."

Responding to the Metro statement, the union flatly called for Wiedefeld's dismissal, saying he was "unfit to do his job."

Forty years have passed since the last Metro workers' strike, a weeklong "wildcat strike," a strike without union leadership authorization, in 1978 that disrupted commutes across the region.

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