Dollar General and Dollar Tree, two of the country’s best-known discount retail chains, warned Thursday that they can’t shield customers completely from higher prices fueled by new tariffs on Chinese imports.

The 25% duties on additional $300 billion in goods, which President Trump is exploring after more than doubling levies on $200 billion worth of merchandise following an impasse in trade talks with Beijing, would cover all of the imports from the world’s second-largest economy. While Trump has described himself as a “tariff man” and maintained the fees are a vital piece of his trade strategy, retailers, economists and some lawmakers have long warned they may hurt U.S. consumers and undermine the benefits of GOP-led tax cuts.