Sunderland chairman Stewart Donald says the club’s seven-figure move for Pompey target Mo Eisa is a ‘fantastic’ offer.
He believes the Black Cats’ bid is better than any tabled by Blues boss Kenny Jackett for the 24-year-old striker.
However, he revealed Cheltenham are yet to respond – despite numerous follow-up calls.
Sunderland have offered more than £1m for Eisa, who netted 25 goals for the League Two Robins last season.
They have also tabled offers for Charlie Wyke and Reading midfielder George Evans as boss Jack Ross bids to boost his firepower.
But former Eastleigh chief Donald told the Roker Report today he is hopeful Cheltenham will accept the move for Sudan-born Eisa.
Donald said: ‘They (Cheltenham) have not come back to us but that bid is strong.
‘I think we have chased them 20 times. As I understand it from the football feedback I’m getting – and I don't know if it’s accurate and Cheltenham would have to confirm – but I think our bid is the strongest bid and the closest to their valuation.
‘I think it’s a fantastic bid for the player. I would hope Cheltenham would accept that and see that as a serious bid. It’s a proper bid.
‘It’s over a million (pounds). I think that will be our biggest transfer. I see people saying we should be in for Jack Marriott but he’s £6.5million apparently quoted and that’s out of our ball park.
‘I said we would have the biggest budget in the league by quite a way. It would be a budget some teams in the Championship would love and that's a fact. That’s what we will have.
‘I also said we would have a transfer kitty that by League One standards is a fantastic kitty and that's what we have got. But there's not many teams in League One spending £6million on a player.’
The News revealed this week Pompey have had several bids turned down for Eisa.
While Conor Chaplin is poised to leave Fratton Park, Jackett has insisted he will not let the 21-year-old go until he has recruited a new hitman.