Second, there's the schedule. The league wants to add two more regular season games, for a total of 18. Players say that would increase their risk of injury, and they deserve compensation. NFL Commissioner Roger Goodell said last month that there are "no deal breakers," but that the status quo is "not acceptable."
Goodell emphasized over the past several weeks that the league and owners understood that a work stoppage would hurt the clubs, the players, the game, the fans and the league's corporate sponsors.
"If we are unsuccessful [in negotiations], uncertainty will continue," he said during a press conference before the Super Bowl last month. "That uncertainty will lead to a reduction in revenue, and when that revenue decreases there is less for us to share," he said, adding that that would make it harder to reach an agreement.
Goodell has pledged to reduce his salary to $1 if there is a work stoppage.
The labor dispute comes after what arguably was the NFL's most successful year. Television viewership was up 13 percent and the Super Bowl was watched by a record 111 million people.
At face value, the dispute looks like a fight between billionaire owners and millionaire athletes, but Ryan Clark of the Pittsburgh Steelers called that view "shameful."
The NFL players are highlighting what a work stoppage would mean for the economy in NFL cities.
In meetings last month with members of Congress, including Rep. Lamar Smith, R-Texas, the chairman of the House Judiciary Committee, and such former NFL players as Reps. Heath Shuler, D-N.C., and Jon Runyan, R-N.J., current and former NFL players focused on how a lockout and canceled season could hurt their communities.
"This Congress is concerned about jobs, jobs and jobs," said Pete Kendall, a former offensive lineman and now a permanent representative on the union's negotiating committee. "A lockout will affect the local economy, not just those who attend the games but those who provide services at the games.
"We're not talking about penalizing players only," Kendall said. "This is going to hurt your parking lot attendants, your restaurants, your hotels. Everybody in your city hurts when this happens."
The NFL insists the changes it is pushing are necessary for the league's long-term financial health.
"This is about the future of our game," Goodell said in January. "There are things that need to be addressed, and we need to address those responsible so that everybody can win."
There are other scenarios that could play out on Thursday. The two sides could agree to push back the deadline, but that seems likely to occur only if they have made enough progress to warrant an extension. The NFL's Pash said that is still an option.
"We're not taking anything off the table," Pash said.