President Donald Trump pledged to bring down grocery costs. But his administration’s policies are contributing to an acceleration in prices, food economists and companies say.

Grocery prices last month rose at their fastest pace in three years, stoked by Trump’s tariffs, a crackdown on immigration, and extreme weather hurting food production. Prices jumped 0.6% in August from the month prior, according to the latest reading from the Bureau of Labor Statistics, and they are up 2.7% from a year ago.

Food prices are deeply personal to consumers, and weekly grocery bills shape their overall perceptions of the economy. More than half of Americans count grocery costs as a major stress in their lives.

Low-income and middle-income Americans, hit the hardest by rising grocery costs, are changing where they shop and what they buy. Companies are also taking extreme measures to appeal to shoppers strained by higher prices, such as bringing back paper coupons.