Ronaldo returned to Old Trafford a year ago and, although he finished the 2021-2022 season as United's top scorer with 18 Premier League goals, he could not prevent the club having a dreadful campaign.
United registered its worst points tally in Premier League history and failed to record a positive goal difference for the first time in more than 30 years.
As a result, United missed out on UEFA Champions League qualification for this season, which seemed to be the root of widespread pre-season reports suggesting Ronaldo wanted to leave.
He was linked with several clubs, including Bayern Munich, Chelsea, Napoli and Atletico Madrid, but no move materialised and he eventually linked up with Ten Hag's squad towards the end of pre-season after missing its tour of Australia and Thailand.
Although there are reportedly no clubs currently interested in him, uncertainty stoked by press speculation continues to cloud Ronaldo's future; and while Ten Hag says he wants the Portugal striker to stay, he was hardly convincing when asked if that will be the case.
Speaking after Sunday's (AEST) 1-0 win at Southampton, during which Ronaldo endured an error-strewn second-half cameo, Ten Hag said: "We plan with him. So we want him to stay. So that is what we want."
Ten Hag was then asked if Ronaldo would definitely remain if he wanted him to stay, and the Dutchman looked unsure as he hesitated to answer.
With something of a shrug, he replied: "I hope so."
The transfer window closes on Thursday, and United is expected to be active in the market before then.
Ajax's Antony and Cody Gakpo of PSV are the two attackers who have been most prominently linked with United in recent weeks, with the former publicly pleading for his club to sell him on Saturday (AEST).