Google is rethinking its mobile payments strategy in light of slow consumer adoption of Google Wallet, sources close to the project told Bloomberg.

Feeling the heat from competitor Isis, Google is said to be courting wireless operators Verizon and AT&T in an effort to expand the service, which is currently only available through Sprint on two handsets.

Google is also said to be redoubling its efforts in advertising and targeted offers to spur adoption of its Wallet app.

According to Mobile Commerce Daily, Google Wallet partners Citi and MasterCard have launched an awareness campaign comprising full page and banner ads within the Pandora mobile app for iPhones. (The slogan: “Tap & Go with MasterCard PayPass and Google Wallet.”)

Citi and MasterCard have also worked with Pandora to create three Google Wallet branded radio stations named after popular shopping methods – “online shopping,” “in-store,” and “out in town.” According to MCD, the user simply drags their shopping method of choice to the “Drag Here” tab and the station automatically launches, replete with Google Wallet pitches.

Google is also considering bypassing wireless carriers and installing its own payment acceptance terminals in stores that would clear Wallet transactions via Google’s servers, rather than rely on the carrier for authentication.

Despite the slow response to Google Wallet, the company says that it is “enthusiastic” about the app’s progress, reports Bloomberg. So far the company has enlisted a number of major U.S. retailers, most recently frozen yogurt chain Pinkberry.

Bloomberg estimates that 50,000 to 100,000 customers have downloaded Google Wallet; however, only a small percentage of those actually use it.

“We knew from the get-go we won’t see a lot of volume,” said Robert Notte, chief technology officer at Wallet partner Jamba Juice. “We are in very early stages of this.”

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