NEW YORK (TheStreet) -- Two months after American Express (AXP - Get Reportlost its lucrative partnership with warehouse retailer Costco (COST - Get Report), the finance company is wooing new customers with a credit card linked to a loyalty program that lets users earn points at one merchant and spend them at another.

The American Express Plenti card, which carries no yearly fee, will let users earn one Plenti point for every dollar spent on eligible purchases at a company in Plenti's network. With the existing network, that means 1,000 Plenti points earned at Macy's (M - Get Report), or Rite Aid (RAD - Get Report) translates into roughly $10 that can be used at, say, ExxonMobil (XOM - Get Report) or Hulu.

The Plenti card will be "compelling to consumers that use these coalition partners, which is why American Express will choose specific partners that are equally attractive to consumers," said Sameer Gokhale, Managing Director at Janney Capital Markets.

New card users aren't the only benefit to American Express, which has 112 million active card users and $34 billion a year in sales. The Plenti loyalty program, which was introduced in March, contributes directly to the bottom line as an initiative of Loyalty Partner, which American Express purchased in 2011 for about 496 million euros ($656.5 million). The first U.S. loyalty coalition, Plenti offers savings from discounts to points that can be earned regardless of payment method and held for up to two years.

The question for American Express investors, however, is how much of a boost Plenti and its branded American Express card can provide after the loss of the Costco partnership, which accounted for 20% of American Express loans and 10% of its cards.

As a revenue source, the co-branded Plenti card has some hurdles: Because it carries no annual fee, the company must rely on Plenti customers to use the card to generate swipe fees. And since American Express charges 3% to 5% swipe fees while their competitors charge just 2% to 3%, its cards aren't accepted as widely.

It also faces a host of competitors from the outset: Reward-based Mastercard (MA - Get Report) and Visa (V - Get Report) cards offer everything from cash-back with use at participating merchants to unique vacation packages and travel insurance.

The loss of Costco, meanwhile, helped spur a slide in the company's stock, which has fallen 13% since the start of 2015, compared with a 2.3% gain in 2014. American Express closed at $79.70 on Monday.

The rest of the year may prove challenging for the New York-based company, which will be working to replace Costco revenue while competing with cash-back and co-branded cards offered by Bank of America (BAC - Get Report), JPMorgan Chase (JPM - Get Report) and Citigroup (C - Get Report), the latter of which which struck a deal to provide Costco-branded cards.

The loss of Costco "is a challenge," American Express CEO Kenneth Chennault said on an April conference call. "It will have a short-term impact on our growth trajectory, but I believe it's a challenge that we can transform into an opportunity."

American Express is working to keep business from Costco card holders, and the company has also renewed branded-card agreements with Delta Air Lines (DAL, Starwood Hotels, British Airways and Cathay Pacific Airways.

The company also has high hopes for the Plenti reward program. "We have a critical mass of powerful brands and there will be more brands to come," Chennault said on the call. "With our strong brand and our long experience in rewards programs, we believe we have an excellent recipe for success."

In addition to Plenti, Loyalty Partner operates Payback, which manages coalition loyalty programs in Germany, Italy, Poland, India and Mexico.

The success of that program, rather than the loss of Costco, is what prompted development of Plenti, said William Tsang, director of corporate affairs at American Express. "American Express was looking to bring the card to the U.S. before the Costco decision," he said.

If the Plenti card proves successful, expect to see competitors like Visa and MasterCard jump on the bandwagon, launching similar programs while at the same time enjoying a larger market share among consumers and merchants.

Chennault said the American Express brand will continue to stand out, though, because it's trusted and "it represents consistency. The 165-year-old company has offered credit cards since 1958, according to its website.

"Our goal has been to ensure that our brand is able to evolve and remain relevant to new segments, and we've been successful to date in making it more welcoming and inclusive," he said.