Nintendo claims to have sold 400,000 Wii U units during the system's first week of availability in the US.
Nintendo of America president Reggie Fils-Aime told CNET that the firm has sold over 1.2 million hardware units in total over the past week including 300,000 Wiis, 250,000 3DS and 275,000 DS systems.
"Wii U is essentially sold out of retail and we are doing our best to continually replenish stock," the executive said. "Retailers are also doing their best to get the product to store shelves. But as soon as product hits retail, they're selling out immediately."
The original Wii sold through to more than 600,000 consumers in the Americas in its first eight days of availability in November 2006.
Fils-Aime also said he doesn't expect shortages to reach Wii levels.
"Wii was a unique phenomenon," he said. "You couldn't walk into a retailer and buy a Wii until spring of 2009. We've certainly learned many lessons from that and we are replenishing retailers more quickly this time around. We are looking to have as much product into retail as possible. It's driven by consumer response."
Fils-Aime claimed over the weekend that third-party games, such as Call of Duty Black Ops 2, look "dramatically better" on Wii U than they do on Xbox 360 and PS3.