A City source said 3i was hesitating over the bid, which is being led by Laing Homes' managing director Steve Lidgate, because it was unconvinced that a buyout was preferable to a traditional sale.
The source said: "It is at a very early stage at looking at this. It is not convinced a management buyout would work."
The emergence of the bid earlier this week ended months of speculation over the future of Laing Homes. Laing, its parent company, wants to sell the housebuilder to focus on PFI deals, and is understood to be asking for up to £400m for it.
Both firms refused to comment.
3i, which backed a buyout at housebuilder Fairview in 2000, was reported to be fully behind Lidgate's move. But the source said the funder was keeping its options open because Laing would be easier than Fairview to disposed of in a traditional sale.
The source said: "It's a different business to Fairview. There was a large landbank at Fairview, but it was brownfield and did not have planning permission. That's a different situation to the Laing one. There's much more goodwill in the Laing deal."
However, one construction analyst said that at up to £400m, Laing Homes was overvalued: "Someone, somewhere, will end up paying a premium. That is fine for a good landbank, but there are no hidden gems."
Prospective buyers do not appear to be worried about the asking price or the relatively short-term landbank. Several are believed to be taking a close look at the housebuilder and are expected to make bids, including Persimmon, Bovis Homes, Wimpey and American firm Centex.
The chief executive of one leading housebuilder said: "It is a well-run organisation and I am sure some of us would be keen to take a look.
"Westbury's purchase of Prowting has proved there is still an appetite for deals if the price and fit is right."