The NFL and the NFL Referees Association have made progress in negotiations on Tuesday and according to sources at ESPN, have reached an agreement in principle to return to work this week's games.

The report cites "sources familiar with the talks," who say that the two sides have been able to work out some of the issues that have been keeping the officials on the sidelines since June.

Sources have said it could take up to a week to get the officials back on the field.

The referees association said that all of its 121 officials are up to speed on the NFL's newest rules and all are prepared to pass, or have already passed their physicals that would allow them to work.

The two sides were able to agree on a range of issues, including a staff of 21 new officials that will serve as a "taxi squad" for overworked crews. The main sticking point continues to be the pension plan and retirement benefits for the officials.

The officials were said to have agreed to the addition of new officials, who will be trained in the offseason and will come from major college football divisions.

The NFLRA has said that they wouldn't allow these officials into the union and that they "would want them compensated by the league if 'they are brought up from the minors' to work a regular-season game."

But while the agreement is optimistic, a deal is not set in stone yet.

According to Peter King at SI.com, these are still issues to overcome before a deal is made, including about the pension plans and retirement benefits.

King also writes that an official who got an email from NFL Referees Association negotiator Scott Green on Wednesday said: "He said we're making progress but not close to a deal right now."

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