Blades boss Chris Wilder wants to boost his squad's Premier League experience after promotion to the top flight.
The 30-year-old could be available for just £2m, according to The Sun.
Middlesbrough are also interested in his signature.
Need a VPN? Or seeking to switch? Then support Tribal Football by clicking here to sign up with our official partners NordVPN. Not only will you receive the best VPN experience, but also great discounts by signing up via Tribal Football. Thanks for your support!