With its Surface Pro tablet selling out quickly in the first weekend of availability, Microsoft moved this week to address supply issues. It says it is shipping 64GB Surface Pro models to retailers in the United States now. And it will deliver more of the eagerly awaited 128GB models “later this week.”

Surface Pro availability has been a key concern, both for potential customers of the tablet and for Microsoft critics, who are eager to debunk any attempts to accurately portray how popular Surface Pro really is. Microsoft admits that “some retail and online locations have been low or out of stock of Surface Pro,” though many Microsoft Store retail locations had hundreds of units, and Apple-like long lines of customers queued up to buy them over the past weekend. (See "Surface Pro Delights, Disappoints at Launch.")

“Demand is high,” Microsoft reiterated on Wednesday. And the supply issues are going to be fixed, it claims.

“In the United States, we are shipping additional units of the 64GB [Surface Pro version] to Best Buy, Staples, and Microsoft Store now,” a blog post credited to the Surface Team notes. “We are shipping 128GB [devices] later this week to retailers, with some units available by the end of the week. Our priority (and that of our retail partners) is to fulfill orders from customers who made a reservation first. Canada is following a similar timeline but may take an extra few days to start arriving.”

“We’re working as quickly as we can to get Surface Pro in market,” Microsoft adds. “If your local retailer does not have stock immediately, they should have it soon.”

Seeking to calm frayed nerves, Panos Panay and other members of the Surface team took to Twitter on Tuesday to answer questions, many coming from customers frustrated by their inability to purchase Surface Pro over the weekend. It appears that many are looking for the device's 128GB version, which is at the center of the availability issues so far. On Twitter, Panay said Best Buy and Microsoft Store locations in the United States would have 128GB units “by Saturday.” He curiously left out Staples, as first noted by my Windows Weekly co-host Mary Jo Foley.