Samsung is adding TD Bank and Regions Bank to Samsung Pay, the company's mobile payments service. Customers in the United States with debit or credit cards from these banks will be able to use their phones to make purchases "soon," according to the company.

The new additions bring the total number of banks and credit unions that support Samsung Pay to 130, which accounts for more than 75 percent of the US market, Samsung says. The company has also said it has registered more than 5 million Samsung Pay users since the service launched late last year, and they account for more than $500 million in transactions.

Still behind Apple Pay, but Samsung has an ace up its sleeve

Samsung's rival service, Apple Pay, has more than 12 million users and is supported by 90 percent of banks in the US. It also has more wide-reaching international support. Samsung has laid out plans to expand to the UK, Brazil, Australia, China, Singapore, and Spain, but is currently only available in the US and South Korea. (Google's service, Android Pay, is rolling out even more slowly, and only accounts for about 1 to 2 million users.)

But the new numbers represent a significant jump from the 70 banks and credit unions that Samsung reported in March, so the gap appears to be closing. Plus, Samsung has an ace up its sleeve — Samsung Pay works on traditional card readers thanks to technology acquired from LoopPay. Apple and Android Pay only work with NFC-equipped point of sale machines.