"Stewart has been frustrated since the summer really, when he signed his new contract," said Downing senior, who also acts as his son's representative.
"He was assured that there would be significant investment in the squad. He feels as though the club have not matched those expectations. He is also frustrated that the team is once again struggling in the Premier League.
"Obviously, as a Middlesbrough lad he has thought long and hard about the decision to hand in a transfer request and he also hopes that the fans will understand his reasons for doing so."
Despite this, Tottenham's hopes of signing Downing were fading after the Teesside club indicated the England international's transfer request would be rejected.
Tottenham manager Harry Redknapp is desperate for Downing to bolster the White Hart Lane club's fight against relegation but struggling Boro are equally determined to hold on to their star player.
Downing's club have so far neither confirmed or denied Downing' transfer request but this lunchtime their website has strongly hinted that the 24-year-old would be told he would be staying at Boro.
Boro manager Gareth Southgate has also spoken to opposite number Harry Redknapp over Downing.
"Harry's got to do what's right for his club and I've got to do what's right for mine," Southgate said.
"Stewart's our best player so we don't feel it would be wise to let him go and I don't think it would look great for him because the club are in a difficult situation and everybody needs to be rallying for the cause."
Southgate added: "Of course he wants to play at the highest possible level and we've always said that if one of the real big-hitters came in for him it would be difficult for us to stop him. But Tottenham are on the same points as us and so there's a lot for us to think about.
"But I'm not under pressure to sell any player. The only way any player will leave is if everyone at every level believes it's the right thing and will help us to climb the table. We're very much together on that."