QPR chief executive Lee Hoos says the club is "appalled by" and "vehemently opposed to" the English Football League's plans for the Championship to return on 20 June.
Hoos says there was "absolutely no consultation" on the matter, claiming clubs learned of the news just before it came out at 21:00 BST on Sunday.
"I am absolutely stunned by this announcement," he added.
No Championship fixtures have been played since 8 March.
"Incredibly, there has been absolutely no consultation with individual clubs nor with the Championship doctors' working group by the divisional representatives - or anyone else in the Football League - regarding this matter," Hoos told the QPR website.
"Having spoken with our director of football Les Ferdinand and our manager Mark Warburton, they share my views. We are vehemently opposed to this schedule."
The EFL said on Sunday that the 20 June date was "provisional" and "subject to the strict proviso that all safety requirements and government guidance is met".
On Monday, an EFL spokesperson added: "The EFL made the decision to announce the proposed restart date of the 2019-20 season following a number of direct approaches from Championship clubs seeking clarity.
"Whilst the league notes the comments made on Monday morning, it should be recognised that there is significant support within the Championship to get back playing as soon as possible in order to finalise the current season from a sporting integrity perspective and lessen the impact on season 2020-21.
"The overall situation remains complex with a number of moving parts to work through in order to get matches in the Championship up and running again, so collectively we need to be flexible in our approach at this time.
"Importantly, we will continue to have regular dialogue and consult with our clubs in the coming days and weeks on all the operational challenges ahead of games restarting - subject, of course, to all safety requirements and government guidance being met."
There are 108 matches remaining in the second tier, plus the play-off semi-finals and final, provisionally scheduled for the end of July.
Hoos added: "The players haven't even returned to full-contact training at this moment and yet they are now expected to be in a position to play at a competitive level in just three weeks' time.
"I have made our feelings known to the EFL and, having spoken with a number of CEOs at other Championship clubs, I am not a lone voice on this matter.
"We are absolutely appalled."
Championship players have been allowed back to training since 25 May, initially while following social distancing guidelines, and full-contact training will begin this week.
QPR are 12th in the Championship - six points from the play-offs and 11 clear of the bottom three with nine games left.
'The news we've been waiting for'
Middlesbrough are just two points above the relegation zone but manager Jonathan Woodgate has welcomed news of the league's return.
The club will return to contact training at Rockliffe Park later this week but will also use the Riverside Stadium to prepare, "just to get the feel of it again".
Woodgate added: "As a club we've made no secret of the fact that we wanted to restart the season when it is deemed safe enough to do so.
"We'd had 20 June in mind as a possible to return and were already working towards that date."
Asked by BBC Three Counties Radio if players would be ready in time for a 20 June resumption, Luton defender Sonny Bradley said: "At this football club, they will be.
"I wasn't sure what sort of shape the players would be in and how far off it they'd be but, looking at the boys last week, we looked sharp and ready to go.
"Obviously we do need a couple of weeks, like every team does, but over the past nine weeks we have been in lockdown but we have also been able to train.
"It has been limited, but on Zoom we've been doing certain training programmes and we've been able to get out, whether it's on the road or on the grass, for 45 minutes and get a training session in.
"I'm pleasantly surprised to see how good a shape that the boys are in. We'll be ready and if we have to play nine games in five weeks, I don't see that being a problem."