North American Wii U sales were reportedly "well under" 100,000 units in January.
The site estimates it sold between 45,000 and 59,000 units last month - "lower than any of the three previous-generation home consoles sold in their worst months, with the possible exception of a recent performance by the original Wii".
NPD did confirm that US Wii U sales for the console's first three months are down 38 per cent from the Wii's numbers at the same point in its lifecycle.
Last month Nintendo lowered its annual Wii U sales forecast from 5.5 million units to four million following weaker than expected demand for the console. However, company president Satoru Iwata moved quickly to rule out the possibility of a Wii U price cut.
Xbox 360 was the best-selling gaming platform in the US in January, the 18th consecutive month it has led overall hardware sales (home and handheld systems) and the 25th straight month it has topped home console sales.