The Democratic nominee for vice president left the campaign trail long enough on Saturday to preside over a course on constitutional law at Widener University’s law school, in Wilmington, Del., where he has taught as an adjunct professor of law since 1991.

Joseph R. Biden Jr.‘s class is co-taught by Robert L Hayman Jr., who told MSNBC that he hopes Senator Biden can return to the classroom after Election Day.

The news network reported that Senator Biden wanted to visit his students on Saturday “as an apology of sorts, since he expects to be actively campaigning through Election Day.”

Mr. Hayman was quoted as saying that there was little talk of the presidential campaign during class: “We talked about separation of powers, we talked about the framers’ vision of the Constitution,” he said. “I think maybe today was refuge from the campaign for him, to some extent, a time for him to be a teacher again.”

When Senator Biden was running last fall for the Democratic presidential nomination, Mr. Hayman told a New Hampshire newspaper, The Keene Sentinel, that the senator was “maniacal” about showing up for the class even during the primary campaign. The profile of the senator also recounted a story of his flying from a debate in Las Vegas to Washington for a vote and then to Wilmington for the class.