For the past few weeks, the Raiders have been trying to hammer out a deal that would keep them in Oakland for the 2019 season, and although there's been plenty of progress in those negotiations, it appears that there's one 'significant' issue that might end up derailing the entire thing. 

According to Scott McKibben, the executive director of the Oakland Alameda County Coliseum Authority, the deal could be taken off the table if the Coliseum Authority isn't able to iron out its differences with the Raiders. 

"We still have one rather significant open issue and I will be going back to the Raiders to discuss that with them and hopefully we'll be able to resolve it, and if we can't, there's a possibility that we won't have a deal," McKibben said Wednesday. 

Although McKibben wouldn't offer any details on the 'significant' issue, the San Francisco Chronicle has reported that the big hang up has something to do with the Raiders training facility in Alameda and the fact that they only pay $525,000 in rent. One thing that's not an issue is the pending lawsuit that the city has filed against the team

McKibben is hoping to resolve the issue by meeting with Raiders president Marc Badain and team owner Mark Davis at some point this week. 

"I'm not going to comment on the particulars of the issues itself. I want to sit down with Marc Badain and Mark Davis and walk them through it," McKibben said. "It's an issue for both of us, on both ends. It requires an agreement by both of us and we have a difference of opinion."

Although there's no deadline to fix things this week, McKibben did say that the Raiders would need to resolve the issue by March 12 so that the city and the Coliseum Authority would have enough time to approve the new lease by March 15. 

"This could very likely put us in a position where there's not a deal," McKibben said. "We're going to have between today and next Monday or Tuesday to resolve it one way or the other."

Besides McKibben's one mystery issue, everything else seems to be a go. The Coliseum Authority executive director said that the deal is 95 percent done on the business end. 

"We're taking the rent up and we're retaining the naming rights for ourselves," McKibben said. "On the business terms of this deal, we're 95 percent there, but there is this one big issue that we need to get worked out."

If the deal gets approved, it could potentially keep the Raiders in Oakland through 2020. The team would pay $7.5 million in rent to play at the Oakland Coliseum in 2019, and then, if the new stadium in Las Vegas isn't ready in 2020, the Raiders would have the option to remain in Oakland one more year by paying a rent of $10.5 million for 2020.  

If the deal doesn't get approved, the Raiders won't have a lot of options for 2019. The NFL needs to know where they're playing so the league can put the 2019 schedule together, which means that Raiders will have to make a quick decision. With Oracle Park off the table -- the mayor of San Francisco doesn't want them -- the Raiders only fallback option might be sharing Levi's Stadium with the 49ers for a year.