Consumers have spent less money on the web this week than experts had anticipated, according to a study, raising concerns that prolonged confusion and anxiety around the US presidential election could hit retailers as the holiday season cranks up.

Online sales during the three-day period from Sunday to Tuesday increased by 31 percent from a year ago to $6.5 billion — more than 4 percentage points less than anticipated, according to Adobe Analytics, which tracks online spending.

Spending on Election Day typically dips compared to the rest of the holiday shopping season. Online sales were down 14 percent the day after the 2016 election, and they dropped 6 percent the day after the 2018 mid-term election.

But this year, prolonged uncertainty about the presidential voting tally could prolong the decline, Adobe said, estimating that online retail sales could drop by $300 million on Thursday alone. According to an Adobe poll, 26 percent of consumers said the outcome of the election will affect their holiday spending.

“Previous election cycles have shown that online growth tends to drop most notably on the day after the election,” said Taylor Schreiner, director of Adobe Digital Insights. “Once a clearer picture emerges in the coming days, we expect to see holiday shopping pick back up shortly after.”

Adobe predicts that online holiday sales will total $189 billion, up 33 percent from a year ago — a jump that would be equal to two year’s growth — as so much shopping has shifted to online during the pandemic.

If another stimulus package is passed consumers could spend an additional $11 billion, Adobe said.