By Simon Evans
Just a day after NFL commissioner Roger Goodell wrote an open letter to fans saying a new collective bargaining agreement "can and will" be made, Richardson painted a more gloomy picture.
"I am not as optimistic as some are that we're making much progress," Richardson, co-chairman of the owners' negotiating committee, told a news conference.
The league risks a damaging work stoppage if no agreement is reached by the time the current pact ends on March 4.
As well as disagreements over cash, the players have expressed concern about increased injury risks if the NFL carries out a plan to add two regular season games to the schedule.
Richardson said that tough economic times meant that there would inevitably be a squeeze on revenues.
"The realities are that states, counties, cities and nationally, things are not well economically and we can't sustain revenue production like we have had in the past. It's just a reality.
"One of the first things that was said to me when I meet with union lawyers is, 'Mr. Richardson, we want more money, more benefits and we want to work less.' And then they say, 'Let's begin negotiations.' And I'm not optimistic we're making a lot of progress," he said.
"In 2006, '07 and '08 we generated $3.6 billion in new revenue. The players have gotten $2.6 billion of the revenue and 32 teams have gotten $1 billion.
"And we have a negative cash flow of $200 million. Now, I don't think many business schools would say that's a model that's going to sustain itself and we have tried to explain that as best we could to the representatives of the Players Association," he added.
(Editing by Steve Ginsburg)