The UFL is experiencing growing pains. In the form of labor pains.

Ben Fischer of Sports Business Journal reports that the spring league’s 24 quarterbacks skipped a recent camp in advance of the launch of training camp on Monday, March 3.

As two sides negotiate, the players’ union contends the most recent proposal, sent on Friday, February 21, entails only a “negligible” increase in last year’s base salary of $55,000.

The next day, the quarterbacks sent a letter to UFL president Russ Brandon and executive V.P. Daryl Johnston. It says, in part: “The proposal our Players Association received on Thursday was unacceptable and insulting. We — all of the quarterbacks in the UFL — have collectively decided not to attend the UFL quarterback training camp this weekend in Arlington, Texas, in [protest] of that proposal and the message that is sent to us as players.”

“The United Football League continues to negotiate in good faith with the players union to finalize a collective bargaining agreement, which will be beneficial both to the players and the league,” the league said in a statement to Fischer.

The players seek a higher salary and year-round health insurance. Until there’s a deal, the players could strike. That would obviously jeopardize the opening of the season, on March 28.

Playing it out, the UFL could hire replacement players. Which would diminish the quality of the product, but would result in games being played as scheduled.