Over a cheeseburger, fried calamari and an “Ivanka Salad” at the Trump Grill in the basement of Trump Tower last week, several aides flipped open a laptop and loaded the popular website 270towin.com, which allows users to create their own winning electoral maps.
For 10 minutes, they clicked through the country, putting Democratic-leaning states won by Mr. Obama four years ago, like New Mexico and Colorado, into Mr. Trump’s column.
Their analysis seemed more atmospheric than scientific.
“You can go to Pennsylvania,” the campaign’s digital director, Brad Parscale, said, referring to a state that polls show favors Mrs. Clinton. “You can almost slice the excitement with a knife. You can feel it in the air there.”