Campbell has started the season in the United first team
Hull chairman Paul Duffen has tabled a bid of £7m for Manchester United striker Frazier Campbell.
The 20-year-old spent seven months on loan at Hull last season and scored 15 league goals as they gained promotion to the Premier League.
Tigers boss Phil Brown has previously stated his desire to bring Campbell back to Hull permanently.
Campbell was in Manchester United's squad against Zenit St Petersburg in the Super Cup final on Friday.
606: DEBATE
Give your reaction to Hull's transfer dealings
Tottenham's Dimitar Berbatov has been heavily linked with a move to Old Trafford, while fellow striker Louis Saha is poised to move to Everton.
While Saha's exit may open an opportunity for Campbell at United, Berbatov's potential arrival could further hinder Campbell's chances of becoming a first-team regular.
Duffen told BBC Humberside: "We've put a £7m bid on the table to Manchester United.
"The complexities of their situation are that it depends on them getting one in, that one might well be Bulgarian."
"As I said all the way through the summer we need to be respectful of that and there's nothing I can do to force the situation.
"If they do bring someone in I want to be at the front of the queue and I will do whatever it takes to bring him to the football club."
"They'll be a lot of people alluding to the fact we've got carried away with ourselves. But I can absolutely guarantee that I'm here for the long term building the football club.
"And we are going to have to get braver in some of the things we do but it will never be at the cost of threatening the security and financial ability of the club long term."
