The Co-operative Group's planned purchase of over 600 Lloyds branches has been thrown into further uncertainty after its chief executive conceded it "may not go ahead".
Co-op is in exclusive talks to buy the 632 branches that Lloyds is putting up for sale in order to comply with European rules on state aid.
But the Co-op chief said regulatory hurdles could scupper the deal.
"There are significant economic and regulatory issues that we have to address and that's what we're working towards," Co-op chief executive Peter Marks told BBC News.
He added the deal is a "very complex transaction" and one the group will "take its time" examining.
A decision will be announced within the next few weeks, he added.
Recently it emerged NBNk - one of the original bidders for the Lloyds branches - may revive its interest in purchasing the outlets amid signs the Co-op deal could fall through.
View from the front row
Project Libra unveiled
Including SJP and investment trusts
Spent two years at Sanlam
Will also assess FCA's actions