The group also announced that it intends to sell its general insurance business, just days after offloading its life insurance arm to Scottish Life's owner Royal London for £219m.
Meanwhile, it emerged that Royal Bank of Scotland is likely to receive up to six offers for the 315 branches it is selling. Richard Branson's Virgin Money, US private equity firm JC Flowers and a consortium of investment funds working with former Tesco finance director Andrew Higginson are among those mulling a bid.
Mutually-owned Co-operative Group as a whole posted a £599m loss for the 53 weeks to January 5 but said that, excluding the banking businesses it is exiting, its underlying operating profit fell to £431m from £523m.
Co-operative chief executive Peter Marks said of the Verde deal: "I know that everybody is frustrated about the timescale.
"We are trying to do the transaction in the worst economic climate you could ever imagine and it is getting worse, not better. That is why it is taking time."
He said that low interest rates were hitting banks' profits and pointed to falling growth forecasts as a sign they might stay low for longer.
He said: "My board are still very keen to seize this opportunity if it can. The thing that we are focused on is risk and the deteriorating economy does not help our case there."
Co-operative has agreed to pay 40%-taxpayer-owned Lloyds up to £750m for the 632-branch portfolio.
It racked up £53m of expenses related to the deal last year.
Lloyds will decide by the end of June whether to continue with the sale.
The Verde portfolio would massively strengthen Co-operative's position north of the Border by handing it the 185-strong Lloyds TSB Scotland network to add to the four branches it already owns.
With Verde's five million customers, Co-operative's share of UK current accounts would rise to 7%. Mr Marks said: "The next few months will see whether or not we can get there."
Lloyds must sell the branches by November as a condition of its state bail-out in 2008 after its rescue takeover of Edinburgh-based Halifax Bank of Scotland.
In August, the Verde portfolio will be branded as TSB.
Lloyds has kept alive plans to instead float the business on the stock market if the deal with Co-operative unravels.
The pressure on Co-operative Bank was underscored by figures that showed it made an operating loss of £257m for the year, against a £176m profit for the previous year.
Co-op said its losses on bad loans, most of them made by the Britannia business Co-operative acquired in 2009, had risen to £474m during the year from £121m.
It took a £150m charge on previous investment it had made.
A further £150m provision was made to cover pension protection mis-selling compensation, bringing the total estimated cost of redress to £244m.
Meanwhile Co-operative said its food business, which it says is the fourth largest grocer in Scotland, returned to sales growth in the fourth quarter of the year after cutting prices.
Underlying operating profit at the business fell to £288m from £318m.