That is the view of Newcastle United legend Chris Waddle, who fears the Toon are set to lose their boss.
Benitez has been at odds with owner Mike Ashley this season and Newcastle are labouring in the top flight.
Meanwhile, Mourinho is under pressure at Manchester United and could lose his job unless upcoming results drastically improve.
United have been linked with Zinedine Zidane and Antonio Conte – two managers currently out of work.
But Waddle reckons Benitez would be a viable candidate for the Old Trafford post – even though the Spaniard managed Liverpool in the mid-2000s.
“I think Rafa Benitez should be a candidate to replace Jose Mourinho at Manchester United,” Waddle told SportingBet.
“He is definitely good enough and has that big club experience having won trophies around Europe. Manchester United might not consider him due to his history with Liverpool, but there’s no doubt in my mind he would be a good choice.”
Benitez steered Liverpool to Champions League glory in 2005 and had notorious run-ins with former United boss Sir Alex Ferguson during his early years in English football.
The Spaniard returned to the Premier League with Newcastle in 2016, having been sacked by Real Madrid earlier that year.
One relegation and immediate promotion later and Benitez is still fighting with Ashley for power over the squad, transfers and a number of other issues.
And Waddle fears the 58-year-old will eventually quit the club unless his situation improves soon.
“Everybody at the club from the players to the fans loves Rafa Benitez and wants him to stay for the long-term, I don’t think anyone would begrudge him leaving in these conditions,” Waddle told SportingBet.
“He is a very talented ambitious manager who is not getting even close to what he wants from Mike Ashley and there’s only so many times you can ignore the approaches from other clubs with looser purse strings.
“Newcastle United are set for a relegation battle this season, there’s no doubt about that.
“Benitez has essentially had the same group of players for the last three years and is being asked to work miracles. The players are performing well, but they aren’t scoring goals.”
Asked if Benitez will still be manager at Newcastle next season, Waddle replied: “I think Rafa Benitez would love to sign a new deal at Newcastle and stay at the club next year, if they can avoid relegation.
“He will have offers from other clubs but he knows how rare it is to have unwavering support from the fans and that’s exactly what he has at Newcastle.
“There will come a point where Rafa Benitez has to leave Newcastle in order to fulfil his own ambitions.
“He wants to compete for trophies and have more freedom in the transfer market, but there’s little sign of that happening at the moment.
“Benitez won’t hang around battling relegation forever.”