Fiserv's ZashPay and CashEdge's popmoney have reported headway among credit unions offering P2P and have struck their own deal with Visa Inc., for example.

Contenders also include tiny startups like Dwolla, backed by Iowa credit unions, and the clearXchange service just announced by industry giants Bank of America, JP Morgan Chase and Wells Fargo.

And at least one other credit union online banking vendor – S1 Corp. subsidiary PM Systems – has already partnered with PayPal, the eBay-owned global operation which last quarter alone reported more than $27 billion in money movement.

"They have a well-known, trusted brand in the P2P payments industry, and their adaptive API enabled us to leverage that into our product, for an end solution that is safe, simple and ubiquitous. Credit unions that deploy this will delight their members and set themselves apart from competitors," said Tim Dolan, WRG president.

"WRG credit unions will be able to offer their users a truly valuable service – the ability to pay any consumer or business instantly in more than 60 countries where PayPal is accepted," said Dan Schatt, general manager of Financial Innovations for PayPal.

WRG said it has a client list of more than 225 credit unions and offers mobile and online banking, remote deposit, alerts, multi-factor authentication, online account opening, ACH and a Symitar Episys service bureau.