HITC Sport understands Plymouth defender is a target for a host of clubs.
Bradley has been an influential figure for Plymouth since joining the club from Crawley Town on a free transfer in the summer of 2016.
The giant defender was a virtual ever-present for Plymouth last season as he helped them win promotion from League Two and, as well as his impressive defensive displays, he chipped in with seven goals for the Pilgrims.
The former Hull City youngster has carried on that fine form into this term in League One and he has made 26 appearances in all competitions for Plymouth so far this season.
Bradley's colossal performances at the back for Plymouth during the last 18 months have won him a host of admirers higher up the football pyramid.
The likes of Bolton Wanderers, Wigan Athletic, Fleetwood Town, Southend United and Doncaster Rovers are all weighing up moves for Bradley as they look to bolster their defensive ranks during this month's transfer window.
The 6ft 5in defender is in the final six months of his contract at Home Park and his suitors are on alert that they could possibly land him for a cut-price fee this month
Plymouth are keen to keep hold of Bradley as they look to maintain their bid for promotion from League Two this season, but they are bracing themselves for interest in the defender before the transfer window closes.