The optimism that once surrounded the possibility of Floyd Mayweather finally fighting Manny Pacquiao no longer seems to be present. The two sides have been negotiating a deal for weeks, and there were signs that they would soon come to an agreement, but talks appear to have hit another impasse.

It’s not exactly clear what the holdup is. Top Rank CEO and Pacquiao promoter Bob Arum blames Mayweather’s side, while Mayweather has remained relatively quiet. There had been a report that HBO might not be agreeable to the terms of a joint pay-per-view, but the network has denied those claims.

"Our position has been consistent throughout this whole process," HBO Sports president Ken Hershman said at Madison Square Garden on Wednesday, announcing the April 25 bout between Wladimir Klitschko and Bryant Jennings.

"We're here to stand by and help wherever we can to make this fight happen. We're not an impediment to that happening, and we'll do what's necessary from our end. Then, it's up to the principals."

Whatever obstacles are in the way of preventing a deal from getting done, they might force Pacquiao and Mayweather to look elsewhere for their next fights. Pacquiao extended the Jan. 31 deadline he gave to Mayweather, but Arum was hopeful that a contract would be signed by now. Mayweather is hoping to fight on May 2 in Las Vegas, and time is running out if he intends to fight on the weekend of Cinco de Mayo.

As Mayweather and Pacquiao potentially make contingency plans, Amir Khan is willing to fight either boxer. The Brit has won his last four bouts, and believes he’s earned a shot at either champ. Khan recently told BT Sport that he’s spoken to Pacquiao and Mayweather’s camp, and he isn’t optimistic that the mega-fight will happen.

"I can't really see that fight happening, there is too much politics with that fight," Khan said. “There's different promotions teams and different management teams - I don't think they will let that fight happen.”

It’s getting late for the two sides to schedule a May 2 fight, but this isn’t unheard of from Maywweather. Khan knows all too well, as he thought he would get a shot at the undefeated boxer in May of last year. Instead, Mayweather decided to take on Marcos Maidana, waiting until the last week in February to make the announcement.

If Mayweather vs. Pacquiao doesn’t happen, Khan might be more likely to face PacMan. Mayweather could be headed for a rematch with Miguel Cotto, as he tries to win a title in a sixth different weight class.