For the second year in a row, Best Buy is offering free shipping on online purchases during the holiday shopping rush.

The promotion, which waives the Richfield-based electronics retailer's usual $35 order threshold to qualify for free shipping, went live on Sunday. It will end on Dec. 24, about a week earlier than last year when it ran through Jan. 2.

"We wanted to do it to make sure we remove any barrier people may have to shopping with us during the holidays," said Best Buy spokesman Jeff Shelman.

Still, while Best Buy is one of the first major retailers to roll out free holiday shipping this year, it's up for debate how much difference it will make in ushering in new sales. Best Buy executives acknowledged last year that most online orders already qualify for free shipping since the store tends to sell pricier gadgets. Still, they noted that the holiday promotion helps simplify the message to consumers.

Last year, online sales accounted for 15.6 percent of Best Buy's U.S. sales in the fourth quarter, which includes the holiday period. A weakness in smartphone sales dragged down comparable sales by 1.7 percent, even while the retailer did better than many of its peers.

The outlook for this holiday season is not too merry as Best Buy continues to fight a downward trend in smartphones. The retailer has forecast no sales growth for the year.

Minneapolis-based Target Corp., which has offered free shipping during the holidays the previous two years, has not said yet whether it will do so again this year.

The free shipping promotions are one more way that many retailers are trying to stay competitive with Amazon.com, whose $99-a-year Prime program has been growing in popularity and offers free two-day shipping to members — and in some cases free same-day or two-hour delivery.

At the same time, Best Buy has also been polishing its shipping game, emphasizing that many of its online orders also can get to customers' homes in two days or less. The retailer now ships many products directly from stores instead of from farther-away warehouses.

Best Buy officials also note that picking up online orders at stores is always free.