President Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE’s approval rating dipped 5 percentage points in the Midwest heading into the latest escalation of the U.S. trade war with China, according to a Hill-HarrisX poll released Wednesday.

The survey, conducted Aug. 23-24, showed Trump’s approval among voters in the Midwest dropped to 39 percent, compared with 44 percent in a similar poll conducted Aug. 18-20.

U.S. farmers, particularly those in the Midwest, have been hit the hardest by Trump’s prolonged trade dispute with China. Beijing has responded to Trump's tariffs by imposing retaliatory tariffs on U.S. goods, particularly agricultural products.

That's prompted more farm groups to speak out against Trump.

The Iowa Corn Growers Association (ICGA) blasted the Trump administration last week, saying the government has put it in “one hell of a bad situation,” and the National Farmers Union condemned Trump for “making things worse.”

The most recent polling results come just days after Trump’s latest round of tariffs took effect.

Trump placed a 15 percent tariff on roughly $112 billion worth of Chinese imports in response to the country's retaliatory tariffs on $75 billion worth of U.S. goods.

The latest round of tariffs also comes amid fears of a potential economic slowdown, which would likely hurt Trump's reelection prospects.

Manufacturing activity shrank in August for the first time since Trump took office, according to a survey released Tuesday. The Institute for Supply Management said its manufacturing index dropped to 49.1 in August, from 51.2 in July.

Trump has defended his trade policies, saying negotiations are going "very well" in a series of tweets Tuesday. He also vowed to get "much tougher" on China.

The Hill-HarrisX poll was conducted online among 1,003 registered voters from Aug. 23-24. The margin of error is plus or minus 3.1 percentage points.

—Tess Bonn