OAKLAND, Calif. -- The minor league Oakland B's planned to take over the Oakland A's venue at the Coliseum for a night of nostalgia in late June -- until the big league club blocked their agreement as exclusive rights holder to the building for professional baseball.

Months ago, before the newly created Oakland Ballers were official and for the most part still just a big dream, co-founder Paul Freedman went back and forth by email some 70 times in an effort to secure one special game at one special venue where he and so many others hold treasured memories dating to their youths.

Freedman said he and co-founder Bryan Carmel had a signed contract in place and deposit paid through communication with ASM Global, which operates the building for the Coliseum Authority -- an agency leasing the ballpark to the A's through this year.

Major League Baseball owners unanimously approved the A's relocation to Las Vegas in November, and the team plans to move into a new stadium on the Las Vegas Strip in 2028. It's not clear where Oakland will play when the Coliseum lease ends.

For now, the A's have exclusive rights to play professional baseball at the Coliseum and declined to grant consent for the Ballers based on their license agreement with the Coliseum Authority. It is a joint powers agency established by the City of Oakland and the County of Alameda.

"We are happy to work with the JPA on other ways to celebrate and promote professional baseball in Oakland," David Rinetti, A's longtime vice president of stadium operations, wrote in an email to ASM Global shared with The Associated Press on Wednesday by the team.

The B's, an expansion club in the independent Pioneer League, were set to begin ticket sales Thursday for a game June 29 against the Colorado Owlz in what they hoped would be "a celebration of Oakland's baseball legacy and the Coliseum" and "a joyful farewell and celebration."

"We began negotiations to play at the Coliseum in July, and by December we had signed our lease and paid our deposit," Freedman said Wednesday. "A few days after Christmas, we were informed that the A's would be enforcing a clause in their contract with the stadium that prevents other professional baseball teams from playing at the Coliseum.

"We are disappointed in this development as we believe this would have been a great event for Oakland. Regardless of this setback, nothing will stop us from turning the page on a new chapter for baseball in the town."

The B's had already reached out to the Oakland Girls Softball League offering free tickets, and local Babe Ruth players and other youth teams were going to receive the same gift.

"My reaction was not surprised and actually a little bit pissed off. But not surprised," said Jorge Leon, president of the Oakland 68s non-profit organization of fans committed to supporting baseball and the East Bay communities. "I think the A's are in a position of embarrassment and again I'm not surprised because I think we would have outdrawn them, we would have filled that place up and I think they're worried and that's why they had to cancel. They had to force their hand."

Organizers aren't ready to give up the idea of one day playing at the Coliseum, not yet anyway -- and Oakland fans have demonstrated their passion this past year for sure.

For now, A's fans are planning their own Fan Fest scheduled for Feb. 24, lining up former slugger Khris Davis and pitcher Mike Norris to attend, and also an actual boycott of the March 28 season opener in which supporters plan to tailgate, gather and celebrate in the Coliseum parking lot but not actually enter the ballpark.

Freedman and Carmel were touched by last summer's reverse boycott by fed-up A's fans, left heartbroken in mid-November when MLB owners voted unanimously to approve the club's relocation. Carmel and Freedman felt called to do something.

"We were inspired by the energy of the reverse boycott night. That game was a protest against the concept that baseball might be leaving Oakland," Freedman said. "It was an important and emotionally healing event for the Oakland community. Our goal with this game is to celebrate that baseball will stay in Oakland for as long as the community wants it to be here."

Bryan Johansen, a fan and co-founder of the charity-focused Last Dive Bar that has raised tens of thousands for community programs in the East Bay, couldn't wait to see everybody back together for a common cause.

"If the A's want nothing to do with the people of Oakland, then at least let someone else do so," he said.

Johansen knows the Ballers will keep fighting.

"I think our Opening Day boycott will show our power that continues to be unionizing the fans," Leon said. "I think that's going to be our show of not quitting and also in the long run if there is somehow a possibility that we can get the Coliseum again, we have no doubt that we can fill up the Coliseum for our baseball team that kind of likes us. We can't wait for the Ballers' season."

Freedman formed some of his fondest memories at the Coliseum, long before the third deck deemed "Mount Davis" was constructed and named for late Raiders owner Al Davis -- and planning this game was about paying tribute to that history, too.

"It's also important for us to specifically celebrate and honor the Coliseum. I love the Coliseum, some of my best memories happened there, and it's hard not to take some of the negative things said about it personally. I think it's one of the best places to play baseball ever constructed," Freedman said. "We'd love for this game to remind people what the Coliseum is all about."