Major League Baseball has proposed cutting the salaries of the highest-paid players in baseball while giving the lowest-paid players full prorated shares in its first economic proposal to the MLB Players Association, sources familiar with the situation told ESPN.

The long-awaited plan, which was delivered to the union Tuesday afternoon, proposes that high-salaried players take significant reductions of what they will be paid during a prospective season, according to sources.

While the size of the pay cuts is unclear, sources said the highest-paid players under the proposal would receive perhaps less than 40% of their full-season salaries.

As word of the proposal spread, players bristled at the notion of taking further pay reductions — particularly ones that would affect the highest-paid players — after a March agreement that they believe guarantees them a full prorated share of their salaries. Under that deal, players would receive slightly more than 50% of their agreed-upon salary over an 82-game season.

MLB has disputed that agreement, believing that the language calls for a good-faith negotiation if games start without fans in the stands, which they would in early July with a deal.

Tuesday’s proposal calls for a sliding scale, as USA Today first reported, that would mirror the pay cuts in some organizations, where the highest-paid employees have taken greater pay reductions, according to sources.