WASHINGTON As the NFL Players Association's executive committee prepared for a meeting today to go over terms of a collective-bargaining agreement, cautious optimism remained that a deal can be hammered out to end a lockout that has lasted more than four months.

But there was no final agreement Sunday night, and a last-minute bid by the players' side to amend terms of the proposed 10-year agreement has led to an unexpected holdup. Two people familiar with the negotiations said the players remain insistent that there be an opt-out clause after seven years.

Such a provision would allow either side to vacate the agreement within a certain time period. In the previous CBA, owners opted out after the 2008 season, making 2010 its final year.

"If this is truly the last item, then (the negotiations are) solved," said a person who has been briefed on the talks. "But there have been a few of those."

Another person familiar with the talks said lawyers and executives from both sides continued to work on contract language, and that it was taking longer than expected.

ESPN.com reported Sunday that the union and the owners had reached agreement, according to sources from both sides.

The website reported that although the agreement will require a majority vote from the players, that part of the deal between the two sides is considered a formality, according to sources.

The National Football Post reported Sunday night that Saints quarterback Drew Brees, a named plaintiff in antitrust litigation against the NFL, had sent an email to teammates that the sides had agreed on a deal. If so, it must be approved by the executive committee today at its headquarters.

Should the players' executive committee vote to accept the deal, it then would go to the 32 team representatives to approve. After that, some 1,900 players would need to vote, with a simple majority required for passage.

There was optimism late Saturday that a deal was imminent after most remaining items were resolved, including the decision by Chargers wide receiver Vincent Jackson not to seek any compensation from the Tom Brady v. NFL antitrust lawsuit.

Jackson, also a named plaintiff, had wanted a $10 million settlement, or the guarantee that the Chargers couldn't use the franchise tag on him.

Another complicating factor is the timing of the players' move to recertify as a union. The league has urged them to vote electronically and speed the process, but the players prefer to sign union cards.

Teams would make them available at training facilities. Players signed cards during the last year authorizing the union to decertify if its leaders chose to do so, and lawyers for the players' side wanted a similar setup for recertification.

Even if a deal is agreed upon today, recertification could delay a return to regular operations.

Only after recertification could a full collective-bargaining agreement be reached. But training camps and exhibitions could occur while the sides put the finishing touches on a deal.

"I think there will be some good news coming out tomorrow," Vikings player representative Steve Hutchinson told the Minneapolis Star-Tribune on Sunday.

The Associated Press contributed