GameStop president Tony Bartel says the US retailer has experienced "slower than expected" Wii U sales since Christmas.
The executive told Forbes: "Following the holiday launch period, sales have been slower than we expected.
"Nintendo plans on launching some of their biggest IP over the next few months which we think will increase gamer interest."
3D Mario and Mario Kart games for Wii U will also be shown for the first time at E3 in June.
Asked what he thinks Nintendo needs to do to compete with Sony and Microsoft this autumn, Bartel added: "Software will play a big role in each console's success over the holidays. We're already seeing great developer and publisher support for PS4, so Wii U will need some great titles, especially first-party titles, to compete.
"There's also a need to increase consumer awareness of the new features available on the Wii U and its tethered tablet features."
In the past few weeks, multiple UK retailers have taken it on themselves to slash the Wii U price in a bid to stimulate sales.
Nintendo president Satoru Iwata flatly ruled out the possibility of introducing an official Wii U price cut in January.