Leeds and QPR are both seeking to bolster their centre-back options before the close of the transfer window and they are considering a move for Hobbs.
Uwe Rosler has been looking for a new central defender all summer to bring to Elland Road, while QPR chief Chris Ramsey is short of options at centre-back after missing out to Fulham for Tim Ream.
Hobbs has established himself as a key member of the Forest side since joining the club on a permanent basis from Hull City in January 2014 after a successful loan spell.
The 27-year-old's progress was hampered by a series of injury setbacks last season restricting him to just 19 appearances for Forest.
Hobbs has started three of Forest's opening five games so far this season and Dougie Freedman would be loath to lose the commanding central defender.
However, Leeds and QPR are both believed to be ready to test Forest's resolve to hang onto the former Liverpool youngster by firming up their interest in Hobbs before the end of the transfer window.