U.S. Bancorp is rolling out new consumer credit cards on the American Express network as the country’s largest regional bank accelerates its card business.

The Minneapolis-based lender and the credit card giant announced their card-issuing agreement Wednesday, saying they expect to launch the new American Express-branded cards by fall 2014.

American Express Co., the country’s largest credit card issuer by purchase volume, still maintains an aura of exclusivity although its “membership has its privileges” marketing campaign is long gone and it offers a prepaid card with Wal-Mart.

U.S. Bank is the latest card-issuing bank to hook up with it. Wells Fargo & Co. announced a similar agreement in August, and industry observers say to expect more such alliances as credit card players fight to grow business in a slow-growth economy where consumers are shedding debt.

“The market is so hotly competitive, it’s now found alliances among strange bedfellows,” said payments industry researcher R.K. Hammer, CEO of the Card Knowledge Factory.

U.S. Bank is a major issuer of credit and debit cards and has long had partnerships with Visa and MasterCard, which it will continue.

Cliff Cook, chief marketing officer for U.S. Bank’s retail payments group, said in an interview that it is working with American Express to develop a number of different products for a range of customers but wouldn’t get specific. In terms of marketing the new cards, the main focus will be existing U.S. Bank customers.

“We expect to have the products available in direct mail, through the branches, certainly online,” Cook said.

U.S. Bank is American Express’ 10th card-issuing partner in the U.S. as Amex works to get more of its cards into a greater range of wallets. It struck its first partnership in 2004 with MBNA, which Bank of America then acquired.

“This is just one part of a global strategy that Amex has been pursuing since 1997,” American Express spokeswoman Nina Chang said of the U.S. Bank deal. “We’re in constant discussion with various banks.”

While some have questioned whether American Express may be diluting its brand, Chang disagrees. “We’re very selective about who we partner with,” she said.

David Robertson, publisher of payment card industry newsletter the Nilson Report, said American Express needs to get more cards out because growth in the cards it issues has been in the single digits.

There are a finite number of people who qualify for an American Express card, he said. Striking alliances with other card issuers is a good way to grow, but it’s incremental growth and not a blockbuster move.

“What it is, is the growth in the number of pieces of plastic on the network,” he said.

For Wells Fargo and U.S. Bank, the American Express cards are part of a general push to woo wealthier customers.

American Express is perceived as a prestigious brand. Its credit card customers are more affluent, spend big and have very low delinquency and default rates, said Bill Harde­kopf, CEO of LowCards.com.

It’s also still perceived as the card to use when you pay your bill off each month. That’s a plus in the postrecession credit environment where more people are using credit cards but paying them off, said Robertson. “It’s still the card used for spending and not borrowing, he said.

Banks also like the bigger interchange fees they get to collect from merchants with American Express card purchases, Robertson noted. Merchants pay higher interchange fees when customers swipe an Amex card as opposed to Visa or MasterCard plastic. That means more ka-ching for the company that issued the card.