Monday's NFL deadline for franchise-tagged players to sign contract extensions with their clubs this year has passed, and the Patriots and receiver Wes Welker didn't strike a deal, according to a source familiar with the negotiations.

That means Welker will play 2012 under his one-year, $9.5 million franchise tender, which he has already signed. The sides can't finalize an extension until after the season.

Welker, who turned 31 in May, is scheduled to become an unrestricted free agent in 2013. The Patriots could once again assign him the franchise tag in 2013, which would be $11.4 million. But, at that point, it might be too rich for the team's liking, especially considering quarterback Tom Brady's cap charge will be around $22 million and the league's salary cap isn't expected to rise much (if at all), setting up a less-than-desirable scenario where the depth-minded Patriots would be devoting about 25 percent of their cap on two players.

Also, the Patriots have other key players scheduled for free agency -- such as safety Patrick Chung and offensive lineman Sebastian Vollmer -- and might be more inclined to use the tag on one of them.

All of which sets up the possibility that 2012, Welker's sixth season in New England, could be his last in a Patriots uniform.

On a day around the NFL in which a handful of franchise-tagged players struck deals before Monday's 4 p.m. ET deadline -- with Chicago Bears running back Matt Forte and Baltimore Ravens running back Ray Rice the most notable -- things were quiet between the Patriots and Welker. As of the weekend, talks were described as quiet, according to a source close to Welker.

The lack of momentum reflected the differences of opinion on the right contract for Welker, as talks had been on and off over the last year.