eBay Inc. said PayPal will be available in 2 million retail stores this year as it takes on Square Inc. and Intuit Inc. in the market for mobile payments.

PayPal has signed up RadioShack Corp. and was in 250,000 stores in April, David Marcus, the president of the division, said at a press event at eBay's San Jose, California, headquarters. More in-store partnerships will be announced soon, he said.

eBay is trying to keep PayPal's growth on track after the unit's sales decelerated to 18 percent in the first quarter from 32 percent a year earlier. By promoting a credit-card reader, PayPal is moving the payments service beyond e-mail transactions for online goods and services and fending off rivals seeking to lure merchants that want to offer customers a way to pay for goods and services via smartphones.

"We had to learn the hard way that offline and getting global acceptance, starting with the U.S. of course, is actually going to take a lot of time and a lot of effort," Marcus said at the event.

PayPal gained 5 million registered users in the first quarter, bringing the total to 128 million.

Appointed by eBay Chief Executive Officer John Donahoe in April 2012, Marcus is seeking to cut back PayPal's bureaucracy, revamp a website deemed boring by users and fix software that makes it hard for merchants to collect payments. Visa Inc. and Google Inc. are also elbowing into the $170 billion market for mobile payments.

Shares in eBay declined 1.1 percent to $55.35 at 2:18 p.m. in New York. The stock had climbed 9.7 percent this year through yesterday.