Johnson added that sluggish spending overall contributed to the weaker-than-expected online sales at Target and Wal-Mart, which also faced increased competition from other online retailers, such as Wayfair.
According to the Reuters/Ipsos poll, 8 percent of adults said they plan to shop only online this year, compared to 6 percent a year earlier. The proportion of respondents who said they would shop mostly online remained steady at 17 percent.
All major retailers are investing in e-commerce.
Target said it has kept up the pace of investment in initiatives needed to grow its online business. In March, the retailer said it will invest $1 billion in improving its online sales technology and supply chain.
Wal-Mart is spending about $1 billion a year to bolster its e-commerce infrastructure. In the third quarter, it opened its fifth fulfillment center dedicated to online sales - establishing a network from which it said it could deliver to customers across the United States in two days.
For many shoppers, Amazon has become synonymous with online shopping. It gained tens of millions of members to its Prime service by offering access to movies, music and other services in addition to free shipping in return for an annual fee.