The NFL and its players union broke off talks again, leaving dozens of veterans in danger of becoming salary cap casualties before free agency begins a minute after midnight Monday.

The breakdown was typical of the topsy-turvy negotiations -- just when things seemed darkest, they got brighter. And when it looked optimistic a deal could be struck, as it seemed early Sunday, talks broke down.

"They're off," NFL vice president Joe Browne said after a day of bargaining that seemed to provide hope of an agreement. Earlier, the league had pushed back the deadline for teams to get under the salary cap from 6 p.m. ET to 10 p.m.

NFL spokesman Greg Aiello said the union broke off the talks and had no further explanation. Union officials could not immediately be reached for comment.

One of the endangered veterans went immediately -- center Kevin Mawae was cut by the New York Jets, although he probably would have been gone anyway because he is 35 and missed the final 10 games of last season with a triceps injury.

Other potential big names to go with a cap at $94.5 million instead of one as much as $10 million higher could be guard Will Shields of Kansas City and linebacker Derrick Brooks of Tampa Bay. Yet another in that category, Jets quarterback Chad Pennington, restructured his contract just before the midnight deadline, to ensure that he would stay with the team.

Most teams had contingency plans for the smaller cap and the larger one. Several, including Washington, the Jets and Tampa Bay were far over the cap.

These negotiations were by far the most difficult since the NFL and the NFL Players Association first agreed to free agency and a salary cap in 1992, ending years of labor unrest that included player strikes in 1982 and 1987. The contract has been extended several times since then, most of the time with ease.

But this time, the players asked for a change in the system.

Until now, they received their money primarily from television and ticket revenues. This time, they requested their share from all team revenues, including outside money generated by everything from parking to stadium naming rights.

That led to difficult negotiations, in part because the teams themselves are having their own dispute over that money because of the disparity in outside income made by low-revenue and high-revenue teams. Union leaders had suggested that it would be hard to reach agreement on a labor contract until the owners settled their own differences.

Both sides had seemed ready to compromise, largely because of the pressure of impending free agency.

It was supposed to begin last Friday but was put off for three days so the sides could continue talking. The talks appeared to be at a standstill last Thursday, when the owners took just 57 minutes to reject the union's last offer.

But seven hours later, the sides reversed course, agreeing to delay the start of free agency for three days so they could continue bargaining. That came as teams who had planned for a larger salary cap were preparing to cut large numbers of veterans.

"Many of those players would have been cut anyway," executive director of the union Gene Upshaw said Saturday, noting that veterans are cut every year but find jobs with other teams. This year, however, the extra cuts could glut the market, causing players to get less money even if they find jobs.