The hedge funds which are about to take a sizeable stake in the bank say they want to keep the ethical policies, as it marks the bank out in the market.
But the Co-op Group wants to make sure it has the final say over any changes to the policy, blocking any future owners from scrapping the rules.
Currently the bank offers accounts to customers whose financial history means they cannot get services elsewhere, at a cost to the bank.
And ex-boss Peter Marks revealed it turns down £2bn of business a year because of ethical concerns over the type of activities it would be funding.
The group wants the bank to keep these policies going, even though it will become a minority owner with 30 per cent of the equity under the plans currently being negotiated.
One possible solution is to write these ethical guidelines into the bank’s articles of association, compelling directors to behave in line with these ethics.
And by including a clause that requires a shareholder vote of 75 per cent or more to change those, the Co-op Group’s 30 per cent share would keep the rules in place permanently.
It is understood this is a key priority in the negotiations.
Meanwhile ratings agency Fitch said the troubled bank is now a less certain target for investors, as the final deal on its debt and equity structure has yet to be worked out.