Hughes brought Wright-Phillips back to Eastlands from Chelsea when he was City manager in the summer of 2008 and is eager to link up with the England winger once again.
"We've enquired, that is well documented, but it seems that it is becoming more and more difficult and more things are being put in our way to stop us being able to conclude that,'' Hughes said.
The stumbling block is reported to be the 29-year-old's wages, which City will not subsidise and Fulham are unwilling to pay in there entirety.
Hughes has, however, brought in Chelsea forward Gael Kakuta on loan until the end of the season.
"He is an exciting young talent and we were pleased we were able to bring him to the club,'' the Cottagers boss added. "He has got good technical ability and pace, which we maybe lack in certain positions.'
Hughes has not ruled out making more signings before next Monday.
"We will look and see what is out there but in fairness we are getting close to the end of the window and anything we get in now we have to be certain it will make a real difference to us,'' he said.
"We have a good group here but if there are other players who have different skill sets who might enhance it we would look at it.''