Amazon is expanding its same-day grocery delivery service to 1,000 cities and towns across the U.S., the company said Wednesday.

The online retail giant plans to expand the service to 2,300 U.S. locations by year’s end in its quest to compete with Walmart.

While the retailer’s same-day delivery expansion leverages its enormous reach online, its fractional brick-and-mortar presence remains a central liability, industry analysts said.