PayPal has signed up 50 merchant acquirers as part of its strategy to move into physical stores, according to Reuters.

However, despite its reach into many of the leading US retailers, the payment giant has made no headway with one of the biggest brands, Wal-Mart, which seems intent on going its own way.

Signing up merchant acquirers, which handle card payments, boosts PayPal’s presence among retailers. In recent weeks Total Systems Services and Heartland Payment Services, two of the largest merchant acquirers, in addition to Vantiv, Worldpay, Global Payments and First American Payments, have signed up, according to PayPal and its partner Discover, the credit card provider.

The payments firm signed an agreement with Discover in August last year. One of its motives was for the card firm to push PayPal as an option for merchant acquirer, who have links to retailers.

The aim is to reach more than two million US retail outlets by the end of 2013. Persuading physical stores to accept PayPal payments is a central part of the strategy backed by CEO David Marcus (pictured).

But not everything is going smoothly with the new strategy. The Wall Street Journal reports that First Data, one of the largest merchants acquirers, is holding out against a deal with PayPal.

However others are willing. Through the tactic of working with merchant acquirers and Discover, retailers including Burger King,  Sephora and Brookstone will start accepting PayPal in their stores before the end of the year.

Discover also has direct links with approximately 1,500 US retailers with whom it has been negotiating to accept PayPal payments.

PayPal is also targeting retailers directly on its own. In January, it claimed to have signed up 23 US retail chains.

However, one retailer resisting PayPal is Wal-Mart. A spokesman for the retailer said “the added complexity at the point of sale does not justify acceptance of PayPal”, which often involves more than swiping a card. For instance, users can authenticate a PayPal transaction by inputting their mobile phone number and a four digit PIN.

However, Wal-Mart is also part of the MCX consortium, along with other leading US retailers, which is developing a rival mobile payments system to PayPal’s.