The U’s chairman stressed that he and the manager both crave success, and whether United can maintain their promotion charge will ultimately determine whether Wilder gets a new deal.
Lenagan believes the former Halifax boss has gone from a ‘good’ to a ‘very good’ manager since the summer.
And the club’s owner says the team’s terrific run of form this campaign more than justifies his decision to stand by the 46-year-old.
Like several key players, Wilder’s contract expires at the end of the season.
Lenagan has an option to extend the deal by an extra 12 months and will hold talks in the new year, as is stipulated in the contract.
He said: “We always said once the year turned we would start to have conversations about next year.
“We have an option in his contract that says we can take him and we have to exercise that by a certain date.”
The U’s chairman, however, did not want to reveal when that date was.
Lenagan handed Wilder a one-year contract in April in the face of criticism from a section of supporters who wanted a change.
It looks a shrewd decision, with United top of Sky Bet League Two and in the third round of the FA Cup.
Lenagan is delighted with what has been delivered so far, while stressing the job is not yet complete by comparing the situation to Wigan Warriors, the rugby league club he also owns.
He said: “If you look at what he has achieved in the last six months, he has recruited very well, he has played young players, has a great team spirit and we are top of the league.
“This is a manager that many people thought couldn’t take us further. I think he has already taken us further in those respects.
“He hasn’t got us promotion yet, but you can’t do that in December.
“I said to Shaun Wane, the Wigan Warriors coach, a year ago, that falling in the semi-final is no good, that is not what you have to do to get your contract extended.
“He won two trophies the following year and got his contract extended.
“Managers recognise they have to win promotion, whether that is by being top or not.
“Chris well understands that is what we are trying to do, but I can’t fault him in terms of the performance improvement he has made in the last six months.
“From a strong base he has gone from being good to very good in my opinion.”
The lack of security was the main reason the United manager spoke to Portsmouth about their vacant position earlier this month, the first time he had made such a move in five years with the club.
And the United chairman believes the situation with Pompey has not had a negative impact on their relationship.
“If anything it has made it stronger,” he said.
“He and I talked about it all the way through very openly and honestly.
“At the end of it we are together and I don’t have a problem with any of it.
“Neither should our fans, it’s not disloyal if you only have six months left on your contract to go and talk to somebody.
“If he was talking to three or four clubs I’d have a different view, but he’s not and I think that loyalty is commendable.”
Lenagan added: “He wants to stay at Oxford, there’s no debate about that, he wants to take us into League One and move onwards.
“There’s no debate whatsoever, if he takes us into League One then he is with us for a good while and he deserves that in every respect.”