Gennady Golovkin was left disappointed after the IBF stripped him of his middleweight world title on Wednesday.
He lost the belt for his failure to fight mandatory challenger Sergiy Derevyanchenko.
Golovkin – who boasts a 38-0 record with 34 knockouts – had a hearing late last month over not agreeing to the mandatory fight. He would have had until August 3 to prepare for the fight, but he never agreed.
The IBF said in a statement that Golovkin fighting "an unsanctioned contest" against Vanes Martirosyan on May 5 was the primary driving force in the decision to vacate the title. He stopped Martirosyan in two rounds at the StubHub Center in Carson, California.
One of the main reasons Golovkin fought Martirosyan in the first place was because Saul 'Canelo' Alvarez tested positive for the banned substance clenbuterol and was hit with a suspension for six months.
Alvarez and Golovkin were set for a May 5 rematch after they previously fought to a draw, but the rematch was cancelled, which led to the latter fighting Martirosyan.
Alvarez's suspension runs out in August, which has him targeting ring return for September 15 as part of Mexican Independence Day weekend.
Golden Boy Promotions CEO Oscar De La Hoya said negotiations for the September bout were dead in the water on Tuesday - after Golovkin refused to back away from demanding a 50-50 split of the money.
However, Loeffler said Golovkin is willing to drop his demands for an even split.
"Gennady has agreed to come off his 50-50 demand," Loeffler added to ESPN. "Gennady wants the rematch with Canelo regardless of what Oscar says. He always wanted the fight with Canelo.
"He will come down to 55-45, which makes Canelo the A side. It will be Canelo making 55 percent in a rematch against GGG, which will be much bigger than the first fight was for sure. The rematch with GGG is his biggest fight by far and Gennady's biggest fight. That's the fight we want."