President Trump was set to rally supporters on Monday in Grand Island, Neb., the last stop in a weeklong swing through Texas, Oklahoma, Alabama and Ohio, every one of them a state he carried by double digits two years ago.

The itinerary, in the final weeks before the midterm elections, tells the story of a party on defense. The president who won Nebraska by 20 points in 2024 is spending October almost entirely in places like it, summoning friendly crowds to rescue a Congress his party already controls. Behind him, Republicans hold financial advantages in nearly every battleground state, and Democrats have grown anxious about being outspent on television across the map.

“Just get out and vote,” Mr. Trump told a weekend crowd in Ohio. “If you do that, we’re going to win and we’re going to win big. And we’re going to shove it up their ass.”

The president has been telegraphing worry about the midterms for a year. “Whether you have a great president or not, Republican or Democrat, they don’t do well in the midterms,” he said Friday night in Mobile, Ala. “I don’t know why. Nobody’s explained it.”

In 2018, his first midterm, Republicans lost the House but narrowly added to their Senate majority. This time, with a bleaker economic picture and a war in Iran dragging on, pessimism runs deeper. “This is a five-alarm fire,” a Republican member of Congress from a state Mr. Trump recently visited told CNN, asking not to be identified to avoid alienating the White House. “We always welcome the president, but I don’t know if he’s aware of the feelings out here.”

At the Nebraska State Fairgrounds, Mr. Trump will stand in the state’s 3rd Congressional District, which he won with 76 percent of the vote in 2024 and which covers 80 of Nebraska’s 93 counties, cattle and farm country. He is skipping the state’s other two districts, both competitive, above all the Omaha-based 2nd, the “blue dot” where Rep. Don Bacon is retiring. It is one of only three districts in the country that Mr. Trump lost in 2024 and a Republican holds.

The rally is meant to lift Senator Pete Ricketts, who faces Dan Osborn, a former union leader running as an independent. “There’s no doubt that high fuel prices put a strain on the budgets for every Nebraska family,” Mr. Ricketts told CNN, saying he welcomed the visit. “That’s one of the things I hear when I travel the state.”

Mr. Osborn lost to Senator Deb Fischer by fewer than 7 percentage points in 2024. This time Democrats are standing down, clearing his path. “The significant difference now between when I was campaigning in 2024 is the war in Iran and costs that are skyrocketing,” he told CNN. “With every single town hall, that’s usually the first thing that gets brought up is the cost of living. It’s tough.”

Mr. Trump’s August decision to allow up to 300,000 metric tons of ground beef into the country at lower tariffs, which he said was meant to bring down grocery prices, drew fierce opposition from Nebraska cattle growers and in Iowa, Kansas and Texas, the rest of the top four beef-producing states. All four hold competitive Senate races in states he won three times. Whether he mentions the policy on Monday will be closely watched.

“This harvest season, with diesel nearly doubled, export markets drying up, rural hospitals struggling, and senseless tariffs still hitting our pockets, Trump would be better served doing his actual job instead of breaking every promise he made to Nebraskans,” said Jane Kleeb, chairwoman of the Nebraska Democratic Party.

On his weekend stops, Mr. Trump made no mention of rising costs. “With the hottest country anywhere in the world, it’s the golden age of America,” he said. His goal, as in 2018, is to make November a choice rather than a verdict on him. “If the Democrats win, you will end up in a 1929-style Great Depression,” he told the Ohio crowd on Saturday night. “We will have a disaster on our hands.”

Grand Island, a city of 53,000, last saw a sitting president on Nov. 5, 2006, two days before that year’s midterms, when George W. Bush landed at Central Nebraska Regional Airport. Mr. Trump won surrounding Hall County by 37 points in 2024. “I’m sure you’ve heard the same predictions I’ve heard,” Mr. Bush said then. “The prognosticators have already decided the outcome of this election before the good people of Nebraska have voted.” He spent the final four days of that campaign barnstorming eight more states; Republicans lost 31 House seats and six in the Senate, in what he later called “a thumping.”