The Major League Baseball Players Association took an initial step toward unionizing the minor leagues Sunday night, sending out authorization cards that will allow minor league players to trigger an election that could make them MLBPA members, union executive director Tony Clark told ESPN on Sunday night.

The potential unionization of the more than 5,000 minor leaguers is the latest action in a years-long effort by players who won a $185 million settlement from the league in an unpaid-wages class-action lawsuit and have received housing from teams and increased pay in recent years. Minor league players, whose compensation and benefits are not collectively bargained, continue to argue for higher salaries, which for a vast majority range from around $5,000 to $14,000. Further, the Senate Judiciary Committee has suggested it will call a hearing to explore MLB's antitrust exemption and its treatment of minor leaguers.

Advocates for Minor Leaguers, the group that has spent recent years organizing minor league players, is now working with the MLBPA, which collectively bargains with MLB on behalf of the 1,200 players on major league rosters.

"The last couple years has been a buildup of players offering their voices and their concerns, with Advocates for Minor Leaguers continuing to echo and aggregate those voices in a way that have gotten us to this point," Clark told ESPN.

In order for the MLBPA to represent minor leaguers in collective bargaining, 30% of players need to sign union authorization cards, which would prompt an election. If a majority of those who vote in an election choose for union representation, the National Labor Relations Board will require MLB to recognize the union. The league and MLBPA then would collectively bargain for minor leaguers, an outcome that even five years ago would've registered as farfetched.

Player representatives on all minor league teams, organized by Advocates through four player-outreach coordinators, will distribute voting cards to teammates. Advocates executive director Harry Marino, who played in the minor leagues for the Arizona Diamondbacks and Baltimore Orioles, said unionization efforts sped up during the 2021 and 2022 seasons as more minor league players expressed interest.

"The time is now because major league and minor league players let us know that the time is now," Marino told ESPN. "It's this group of players at the minor league level that have been pushing this over the past couple of seasons, and the major league players took notice and ultimately decided to take this step."

MLB declined comment Sunday night.

Multiple major league players told ESPN they were surprised by the news that the MLBPA would potentially expand its membership by nearly five times. The union plans to hold a Zoom call Monday to answer questions from players.

"Major league players have an enormous amount of power within this game," Marino said. "And knowing that major leaguers have their backs is really what makes all the difference for the minor league guys."

Minor league players said conversations around union representation changed with more players openly speaking about their living conditions privately and publicly. Amid the growing momentum, the MLBPA provided substantial financial support, according to sources, committing $1 million in 2020 to organizations providing support to minor leaguers, including Advocates and More Than Baseball. The donation paid the salaries of Marino and Kevin Slack, a former Democratic political operative who joined Advocates as director of communication and development.

The treatment of minor league players emerged as a seminal story in recent years with the potential damages the certification of the Senne v. MLB antitrust suit posed for the league as well as the stories of players receiving salaries below the poverty line and living in poor conditions. While unionization existed as a possibility to potentially remedy some issues, the fear of risk long prevented players from organizing. Whether it was concerns about teams destroying individuals' careers or the difficulty in finding consistent leadership among a constituency that constantly changes, the obstacles proved formidable.

The distribution of union authorization cards will put at least a portion of that theory to the test. Multiple minor leaguers have said players are becoming more educated on their labor rights and how MLB's antitrust exemption affects their employment status.

"The game of baseball will be better for everyone," Marino said, "when minor league players have a seat at the table."

Clark expressed confidence about the vote passing for the MLBPA to represent minor leaguers because of the feedback he received from players.

"Listening to the players and the concerns that they voiced in their interest in creating a formal seat at the bargaining table, they give me confidence," Clark said. "The players always give me confidence."

ESPN's Joon Lee contributed to this report.