The two-story house, painted like an American flag and with a giant Trump lawn sign, was a semifamous roadside attraction in 2016. Hundreds of people detoured an hour outside Pittsburgh to take pictures there, and Donald Trump himself tweeted an image of the “Trump House.”

Now another election season is underway, and Lou Barletta, the Republican candidate for Senate in Pennsylvania, has cast himself in the Trump mold, hoping to win statewide the way the president did.

The Trump House is still in the same place. But the voters may not be.

Across the street, three factory workers on a lunch break last week said they had not even heard of Mr. Barletta, who forged his political identity as the mayor of a small city at the other end of the state that he vowed to make “one of the toughest places in the United States” for illegal immigrants.