Sheffield United: Chris Wilder keeps up the pressure on top targets
Although manager Chris Wilder is unwilling to pay an inflated fee in order to secure Osborn's release, he is understood to have instructed intermediaries acting on his behalf to leave United's opening offer, thought to be in the region of £3mm on the table.
With the player's contract at The City Ground sent to expire next summer - Sabri Lamouchi's side unable to offer him top-flight football - Wilder believes maintaining the pressure on Forest to return to the negotiating table will eventually pay dividends.
United are using similar tactics in the battle to secure the release of Oli McBurnie and Neal Maupay from Swansea City and Brentford respectively.
McBurnie, who despite representing Scotland at international level was born in Leeds, is keen on exploring the possibility of a move to South Yorkshire. Sources close to Maupay suggest he is also interesting in learning more about United's proposal, despite also counting Seville and Aston Villa as admirers.
United, who are training in Portugal ahead of Friday's friendly against Real Betis, began their preparations for the new season by signing Luke Freeman from Queens Park Rangers before Phil Jagielika returned to Bramall Lane, where he started his career, following a 12 year spell with Everton.
Dean Henderson, the Manchester United goalkeeper, also features among Wilder's list of targets.
Osborn joined Forest’s youth system from arch-rivals Derby County in 2003 and has been capped by England at youth and under-20 level.