With a fortune estimated at more than $200 million, Sen. Pete Ricketts, R-Neb., is among the richest members of Congress. His independent challenger, Dan Osborn, reported an income last year of $108,089.91 from the heating and air conditioning company where he works as a mechanic.

That yawning gap, between a middle-class salary that is falling behind inflation and generational wealth that has soared over the past two years, is at the heart not just of Nebraska’s competitive Senate contest but House, Senate and governor’s races across the country. It’s not just the price of gas and groceries. It’s about those who struggle watching in wonder at those who don’t.

“The perspective has changed from left versus right,” said Jim Begley, director of the William Brennan Institute for Labor Studies at the University of Nebraska-Omaha. “Now it’s top versus bottom.…