A number of NFL owners hope the proposed collective bargaining agreement doesn't pass with the players because they believe they can negotiate a better deal with eyes on an 18-game season in the future, a league source told ESPN's Jeremy Fowler on Saturday.

"They think they can get a better deal next year," the source said. "They feel they gave up too much on the economics."

The owners told commissioner Roger Goodell of their belief at an owners meeting in New York in February, citing frustration with the players' monetary increases and the increase in the size of active rosters.

The owners approved the proposed CBA last month, though ESPN reported at the time that the vote was not unanimous. Three-fourths of the owners had to approve the CBA for it to be ratified.

Players have until 11:59 p.m. ET Thursday to cast their votes on the proposed CBA via DocuSign. The CBA will pass if it receives a simple majority (50% plus one vote) of ballots sent in. The agreement would be in effect for the 2020 league year, but the possible 17th regular-season game would not be added until the 2021 season at the earliest.

If the CBA is approved, the NFL regular season could not be expanded past 17 games through the life of the deal, which would run through the 2030 season.

But a handful of owners want an 18-game season eventually, and that could come up in future negotiations if the players don't approve the CBA next week.

In July, NFL Players Association executive director DeMaurice Smith acknowledged that the NFL had raised the idea of an 18-game schedule in early labor negotiations, but he said he didn't see it happening.

"I don't see an 18-game schedule -- under any circumstance -- being in the best interest of our players," Smith said at the time. "If somebody wants to make an 18-game proposal, we'll look at it. I haven't seen anything that makes me think that it would be good for the players."