Tariffs from the Trump administration have dramatically changed the e-commerce landscape in the U.S., with 34% of consumers saying that they've delayed making purchases until there's more certainty.

According to a survey of 1,000 U.S. consumers from consultancy firm Alix Partners, Americans are reporting a decline in online purchases across all categories (except groceries) for the first time since the survey's inception in 2012. Consumers have been frugal with big-ticket items too, with online purchases over the last 12 months falling by double digits for sporting goods, furniture, home furnishings and large electronics. 

"Shippers, carriers, consumers — they're all feeling the effects of geopolitical unrest, spiking oil prices, economic uncertainty and trade turmoil," Alix Partners said. 

Read More: Rethinking Supply Chain Strategies in a Time of Tariffs

Tariffs have been particularly front-of-mind for shoppers, with nearly 30% reporting that they've made online purchases earlier than planned over the last six months to get ahead of potential levies. Another 22% said that they've either reduced or delayed online purchases shipped directly from overseas due to tariff concerns. Retailers have been feeling the strain as well, with 72% of 100 executives surveyed by Alix Partners saying that e-commerce has not been a profit driver, and 76% saying that their per-package delivery costs have gone up over the last year.

Retailers are looking to address added costs by diversifying their carriers, with 40% having shifted package volumes away from FedEx or UPS in the last year, and 15% planning to offer in-store pick-ups to cut down on delivery costs. Roughly 85% said that reducing the total cost per order is their top priority for last-mile delivery.