It's understood the 49-year-old is becoming increasingly disillusioned with life at the Santiago Bernabeu, while some high-ranking officials are equally fed-up with the outspoken Portuguese coach.
"Is Mourinho going to stay at Real at end of season? He has already decided to leave in my opinion," said Calderon in an interview with BBC Radio 5 Live.
"I'm not certain but in my opinion he's fed up with what's happening and some people are fed up with his attitude and behavior. I believe he's already made his decision to leave."
Calderon, who was president at Real Madrid between 2006 and 2009 - prior to Mourinho's arrival in the Spanish capital - also criticized the 'Special One' for his behavior, saying that it does not sit well with the club's history.
"I think his behavior hasn't at times been approbate to Real Madrid's history," he explained. "The problem with Mourinho - and he is an amazing coach - is sometimes he has done things that aren't approbate with Real history.
"Complaining many times about referees and UEFA, pushing the players against their rivals to give them enemies. That's not Real Madrid."
If Mourinho does leave the La Liga giants at the end of the 2012/13 campaign, the next question on everybody's lips will be where next for the Portuguese tactician?
A return to former club Chelsea could be on the cards, after Roman Abramovich parted company with Roberto Di Matteo yesterday, just six months after he lifted the Champions League trophy with the Blues.
Rafael Benitez has been appointed as interim manager on a six month contract, but the Russian owner might want to turn to the man that delivered two Premier League titles, one FA Cup, and two League Cup trophies, if he fails in his pursuit of bringing ex-Barcelona boss Pep Guardiola to Stamford Bridge.
Mourinho has also been touted as the natural successor to Sir Alex Ferguson at Manchester United, when the 70-year-old Scot finally calls time on his Old Trafford tenure, which now extends over 26 years.
Another possible option could be the Red Devils local rivals Manchester City, who would certainly have the budget to offer Mourinho a competitive salary to take over at the Etihad Stadium.
With the noose tightening around Roberto Mancini's neck after City's acrimonious Champions League exit at the expense of Real Madrid last night, Sheikh Mansour could task the current Los Blancos boss with building on his club's domestic success by delivering European glory.
In the aftermath of the 1-1 draw between Manchester City and Real Madrid, Mourinho had another dig at Mancini, claiming that he would have been sacked had he failed to get Real Madrid into the last-16.
"I admire the fact that clubs support their manager," he said. "City is out of Champions League. But Real Madrid and Borussia Dortmund are very good teams and we knew a big team would be out.
"It is good that it was City because Roberto can work without any kind of problem I believe. If it was Real Madrid, the press wouldn't let me return to Madrid."
Either way, Mourinho is likely to have the last laugh, and if Calderon is to be believed, will walk away from the Santiago Bernabeu at the end of the season, marking the end of another chapter in his illustrious career.