NEW YORK (AP) — Major League Baseball is ready to voluntarily accept the formation of a minor league union, a key step that will lead to collective bargaining and possibly a strike threat at the start of next season.

The Major League Baseball Players Association launched the unionization drive on Aug. 28 and told MLB on Tuesday it had obtained signed authorization cards from the approximately 5,500 players with minor league contracts. If MLB had declined to accept the union, the players’ association’s next step would have been to ask the National Labor Relations Board to conduct an authorization election.

“We, I believe, notified the MLBPA today that we're prepared to execute an agreement on voluntary recognition. I think they're working on the language as we speak,” baseball Commissioner Rob Manfred said during a news conference Friday to announce on-field rules changes for next season.

Both sides were exchanging language Friday for a proposed card-check agreement. MLB maintains players with Dominican Summer League contracts will not be included in the bargaining unit, while the union would not state its position.

“We are pleased Major League Baseball is moving forward with this process in a productive manner," union head Tony Clark said in a statement. "While there are significant steps remaining, we are confident discussions will reach a positive outcome.”

Major leaguers negotiated their first collective bargaining agreement in 1968. They have had nine work stoppages during a period of gains that saw the big league average salary rise from $19,000 in 1967 to over $4 million this year. Players on 40-man rosters on option to the minor leagues have been represented by the union since 1981.

The vast majority of minor leaguers have not previously been represented by the union, which intends to form a separate bargaining unit with its own dues and governance structure, such as player representatives and an executive board.

MLB raised weekly minimum salaries for minor leaguers in 2021 to $400 at rookie and short-season levels, $500 at Class A, $600 at Double-A and $700 at Triple-A. For players on option, the minimum is $57,200 per season for a first big league contract and $114,100 for later big league contracts.

In addition, MLB this year began requiring teams to provide housing for most minor leaguers.

MLB and union negotiators have had an acrimonious relationship in recent years, leading to several grievances that remain pending. Manfred and Clark held separate news conferences to announce the agreement that ended the lockout in March, and union officials did not attend MLB’s news conference Friday to announce the adoption of a pitch clock and defensive shift restrictions next season.

The five-year labor agreement expires on Dec. 1, 2026, and MLB could seek a simultaneous expiration for a minor league deal.

The minor leaguers’ greatest leverage may be ahead of opening day, March 31 at Triple-A and April 6 at lower levels, when a strike could lead each team to keep its dozen or so unionized players on option at training complexes playing makeshift games.

Negotiations between Deputy Commissioner Dan Halem and Bruce Meyer, recently promoted to the union’s executive director, have been filled with acrimony.

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