Preston, Blackburn and Cardiff have all shown interest in the Republic of Ireland international over the summer.
However, Curtis is facing up to the growing possibility that he will not be leaving Fratton Park during the current window.
Pompey have long made it clear that they have no intention of parting with the winger at the last minute, thereby inevitably sparking a desperate scramble for a replacement.
That scenario looks unlikely, though, with little apparent movement from interested parties at present ahead of Tuesday’s 11pm deadline.
The News understands there is now an acceptance from both sides that Curtis will remain with the Blues, despite being keen to test himself at Championship level.
That will come as a blow to the 25-year-old – but will delight Danny Cowley knowing he has a player of Curtis’ calibre still at his disposal.
The winger flew to Portugal on Sunday to link up with the Republic of Ireland squad ahead of forthcoming internationals against Portugal, Azerbaijan and Serbia.
During his Fratton Park absence, there remain lingering hopes that late transfer developments may still occur.
Yet in a window in which Fulham, Middlesbrough, QPR, Stoke and Swansea are the only Championship clubs to have paid transfer fees, it doesn’t look realistic.
Pompey have been keen on receiving around £2m for the Irishman they recruited for a bargain £100,000 in the summer of 2018.
Yet the coronavirus pandemic’s influence in depriving match-day revenue for 18 months has significantly reduced the financial outlay of clubs, particularly in the Championship.
And with Curtis’ contract ending in the summer of 2023, the Blues have no need to accept a cut-price deal during the current window.
Throughout the uncertainty of whether he would stay at Fratton Park, the ex-Derry man has earned praise from Cowley over his positive attitude and commitment.
Nonetheless, it has been a disappointing start to the campaign from Curtis, who has still to either score or assist in the opening six matches.
Indeed, that return will have done little to convince Championship clubs to splash out a large transfer fee on acquiring him before the window closes.
The lack of goals among his team overall is a growing concern for Cowley, whose side have registered successive blanks during trips to Doncaster and Wigan.
Curtis has so far totalled 40 goals in 148 appearances during his Pompey career.
A message from the Editor, Mark Waldron
The News has launched a subscription offer which gives you unlimited access to all of our Pompey coverage, starting at less than 14p a day.
You can subscribe here to get the latest news from Fratton Park - and to support our local team of expert Pompey writers.