SAN DIEGO -- Speaking to minor league baseball's executives about a controversial proposal to contract 42 teams, MILB president and CEO Pat O'Conner delivered a blistering rebuke of the plan.

"We cannot allow ourselves to be splintered for this next deal," O'Conner said. "No one's future is safe, unless all of your futures are safe."

In his annual address during the opening session of the minor league winter meetings, O'Conner began by ticking off the general health of MILB, which saw a year-over-year increase in attendance to 41.5 million during a time when in-venue attendance is dropping across the sports landscape. Nineteen teams set single-season attendance records. Bottom-line revenue is expected to be up.

"Big storm clouds loom on the horizon," O'Conner said, abruptly changing the tone of his speech with that sentence.

According to the proposal from Major League Baseball, as first detailed in October, 42 teams would lose their MLB affiliation when the current Professional Baseball Agreement expires on Sept. 15, 2020. The remaining teams would be realigned into leagues that maximize the proximity of each affiliate to its big-league parent.

In addition, the draft would be pushed back to mid-August and rather than deploying new draftees in short-season Rookie Leagues, teams would send their new players to major league spring training facilities to receive analytically-based training.

Other proposed changes include a new "Dream League" venture that would be created to fill the void opened by contracted teams. Clubs in that circuit would operate similar to an independent league, though it would be co-owned by MLB and MILB. Also, the number of players a major league organization can have under contract at any one time would be drastically reduced to 150.

MLB has suggested that the changes are needed due to poor facilities in some communities, a need for enhanced player health services, better pay and reduced travel.

"I for one am not comfortable with conceding the notion that we need such radical change," O'Conner said near the end of his speech. "Do we need a tweak? Absolutely. Do we need to refine the way we do things? Yes. Do we need to work on our facilities, travel, player health and welfare? Yes.

"And we have told the other side that we've always agreed that those are items that are central to the next agreement. We are in agreement that there is a need for improvement in those areas."

Still, in often bombastic language, O'Conner insisted that any proposal that would impact the number of teams or end the long histories of many of the teams that might be subject to contraction won't be tolerated.

"We are baseball's first touch point for millions of kids in this country," O'Conner said. "We are the first baseball experience for millions of American families. In many cases, we are the only touch point for baseball for millions of fans.

"It seems to me that minor league baseball's future is under an existential threat as we negotiate this next baseball agreement. The next agreement will cover a specific period of time, as is traditionally the case. That's not new. What is unique is the next agreement could be the most important agreement that we have signed in the last 50 years."

The speech, along with an address from MILB vice president Stan Brand that preceded O'Conner's, seemed to lay out a two-fold strategy to brace for the ongoing negotiations, beginning with the need for minor league clubs and leagues to act as a unified entity.

"I assure you the power of one, in this current environment, is never more important than it is today," O'Conner said. "This situation reinforces the power of one, not only as mantra to success, but it's our mantra to survival -- as individual teams and as an organization. We should never be divided in our resolve to represent grassroots American and provide affordable, family entertainment to over 80 percent of this country."

Another key tool for MILB in the negotiations is political might, according to Brand.

"There is no other group engaged in Washington that enjoys the level of good will, appreciation and respect that minor league baseball does," Brand said. "It is genuine. It is universal. It is unbent."

As details about MLB's proposal began to circulate, several politicians, including presidential candidate Bernie Sanders, spoke out against it. Independent analysis of the proposal, such as the one from Fangraphs.com, have estimated that as many as 16 million fans could lose easy access to live baseball under the proposal.

O'Conner and Brand have helped lead lobbying efforts that culminated in last week's announcement of the bipartisan Save Minor League Baseball Task Force in Congress.

"For us, it's never been just about our business," Brand said, speaking to the gathered team officials. "It's been about community, embracing our fans and their interests. We have a long road ahead, but I can assure you of one thing: the support we have across the political landscape -- that you've built through your charitable work, your commitment to diversity and the appreciation you play in your role in the community -- has never been higher, or more critical to the survival of minor league baseball as we know it."

Last week, Sanders met with MLB commissioner Rob Manfred to discuss the proposal and the negotiations. Sanders, a senator from Vermont, sent Manfred a letter on Nov. 25 calling the plan "an absolute disaster for baseball fans, workers and communities throughout the country."

After the meeting, MLB released a statement, saying it "understands that we have an obligation to local communities to ensure that public money spent on minor league stadiums is done so prudently and for the benefit of all citizens.

"MLB also must ensure that minor league players have safe playing facilities suitable for the development of professional baseball players, are not subjected to unreasonable travel demands, are provided with compensation and working conditions appropriate for elite athletes, and have a realistic opportunity of making it to the major leagues."