President Trump traveled to a General Motors facility in Milford, Mich., on Monday, opening the final 100-day sprint to the midterm elections with a stop in a purple congressional district that Democrats have targeted as a rare pickup opportunity in a narrowly held House.

The visit tests whether the president's tariff-and-jobs message can defend a swing seat that his approval ratings, gas prices above $4 a gallon and lingering inflation have left exposed, even as fresh Gallup polling shows economic pessimism easing for the first time in months.

The Milford stop puts Trump in the district of Republican Rep. Tom Barrett, whom a crowded field of Democrats is lining up to challenge in November. "The president pledged to put Michigan workers back to work, and he's doing it," White House spokesperson Liz Huston told Semafor.

The auto-plant visit coincides with the ceremonial opening of the Gordie Howe International Bridge between Detroit and the Canadian province of Ontario. A joint U.S.-Canada ribbon-cutting planned for the same day was called off last week after Trump renewed his trade war with Ottawa, imposing 50 percent tariffs on Canadian autos, dairy and alcohol under a 1930 trade-discrimination statute.

The polling

Gallup's economic-confidence index rose to minus 31 in July from a low of minus 45 in May, with the pollster attributing the shift largely to Republicans and independents. Gallup found 22 percent of Americans now rate U.S. economic conditions as excellent or good, up from 16 percent in May. A plurality — 44 percent — still call conditions poor, and more than two-thirds say things are getting worse. The poll was in the field July 1-19, a stretch in which Brent crude traded near $100 a barrel and the national gasoline average sat above $4.

The campaign

Rep. Suzan DelBene, the Washington Democrat who chairs the Democratic Congressional Campaign Committee, told CNBC her party would spend the closing 100 days pressing an affordability message. "We have great candidates. We have the momentum. We have the message," DelBene said. She added that Republicans "are a rubber stamp for Donald Trump."

Republicans control the House by a narrow margin. DCCC officials view Michigan seats such as Barrett's as central to any path back to the majority, and DelBene said cost-of-living pressures — housing, food, health care, child care, energy — are the party's ballot-box wedge.

The National Republican Congressional Committee declined to make its chair, Rep. Richard Hudson of North Carolina, available for an interview with CNBC. Mike Marinella, an NRCC spokesperson, said Republicans hold "a more favorable map, stronger candidates, a deep fundraising advantage, and a winning message that serves as a stark contrast to Democrats' radical turn to socialism and messy infighting." Gallup credited Republicans and independents — not Democrats — for the July mood improvement.

DelBene said Democrats intend to press the affordability case every day until November. Trump's Milford stop signals the White House will answer with plant visits and infrastructure openings in the swing districts that will decide control of the House.