FOXBOROUGH, Mass. — The San Francisco 49ers are now willing to listen to trade offers for Brandon Aiyuk and have given the star wide receiver permission to negotiate a contract with other teams, sources told ESPN.

The 49ers did not have the same willingness to listen to trade offers at the start of training camp, so this represents a significant change in San Francisco’s stance.

The New England Patriots and Cleveland Browns both have been in contact with the Niners and are interested in trading for Aiyuk, sources told ESPN. The Pittsburgh Steelers also were interested but, barring a change, do not appear to be a potential trade destination any longer, according to sources.

The Patriots have been attempting to acquire Aiyuk for months, and it has been a slow process from their side, according to sources.

The multiple dynamics have created a situation that could lead in several directions, including Aiyuk staying with the 49ers and playing out the fifth-year option on his rookie deal that would pay him $14.124 million.

One significant factor is Aiyuk agreeing to a contract with another team. Other teams are willing to pay Aiyuk more than double the value of his $14.124 million fifth-year option, but he has balked so far at multiple contract offers, according to sources.

The 49ers also have to be comfortable with any trade compensation, and sources told ESPN that the reigning NFC champions are willing to keep Aiyuk.

NBC sports Bay Area reported late Monday night that the 49ers have “negotiated the framework of trades” that would send Aiyuk to the Patriots or Browns.

Aiyuk, 26, reported for the 49ers’ training camp but has not practiced as he seeks a new deal.

The Patriots’ lengthy pursuit of Aiyuk traces to executive vice president of player personnel Eliot Wolf sharing his hope to “weaponize the offense” in the offseason. The Patriots selected Drake Maye with the No. 3 overall pick in the draft, and one of their goals has been to surround the former North Carolina quarterback with more talent to aid in his development.

New England attempted in March to sign free-agent wide receiver Calvin Ridley, who ultimately landed with the Tennessee Titans on a four-year, $92 million deal.