WASHINGTON — With a looming sense of a debacle in the U.S. midterm elections, some Democrats are rationalizing a silver lining: It may not be a bad thing if Republicans win control of at least one chamber of Congress on Nov. 2.

Then, the argument goes, the opposition would be responsible for governing decisions, and its positions — for privatizing Social Security, rolling back health-care benefits and giving huge tax cuts to the wealthiest Americans — would backfire.

The Democrats would come roaring back two years later. The model is President Bill Clinton’s re-election in 1996, two years after Republicans took over Congress.

Those who were there in the mid-1990s have a different view. “It would be an unmitigated disaster for us,” says Tom O’Donnell, a Democratic political consultant. He was the top aide to Representative Richard A. Gephardt of Missouri, the House Democratic leader in that earlier period, and remembers the nightmares it caused him.