Dana White's hopes of holding a rematch between Francis Ngannou and Derrick Lewis for the UFC heavyweight championship this summer appear to be fading away. 

Per MMA journalist Ariel Helwani, the second bout between Ngannou and Lewis being targeted for Aug. 7 is considered a "long shot" right now because of scheduling conflicts. 

Helwani noted a September date could be worked out between the two fighters. 

White told TSN in May that a bout between Ngannou and Lewis "is going to happen this summer.”

That comment came after some hoped that UFC could work out a deal to have Jon Jones move up in weight class to challenge Ngannou. 

Jones said in an April interview with FightHype (h/t ESPN's Brett Okamoto) that he was optimistic about fighting the Predator for the heavyweight crown at some point. 

"I think it's going to happen," Jones said. "I think the UFC will eventually do the right thing. This is one of the greatest fights of our generation, and it would be really sad if it weren't to happen. It would be a real tragedy. All in good time. We're patient."

White said on The Bill Simmons Podcast (h/t Alexander K. Lee of MMAFighting.com) that UFC moved off a potential Jones-Ngannou match because he claimed Jones wanted "$30 million guaranteed" to sign up for the fight. 

Ngannou defeated Stipe Miocic via second-round knockout at UFC 260 in March to win the heavyweight title for the first time in his career. The 34-year-old has won each of his last five fights dating back to November 2018. 

The last person to beat Ngannou was Lewis by unanimous decision at UFC 226 in July 2018. He is in the midst of a four-fight winning streak.