Mr. Reid emphasizes that he is not angry or bitter. But he says he feels so disconnected from Washington that he is selling his apartment in the Ritz-Carlton here and plans to be in the nation’s capital only infrequently.

“I don’t want to be here,” Mr. Reid said. “My life’s not the Senate anymore.”

To some, that is no doubt good news. Mr. Reid was a tough adversary, an acerbic foe always ready to slug it out with Republicans, and he left behind many detractors when he retired at the end of 2016.

Now, like previous Washington figures who either exited voluntarily, as he did, or were unceremoniously shown the door, Mr. Reid is discovering that once you are out, you are really out. Of course, there is always sticking around to lobby — “I would rather be taken to Singapore and caned” is his quip on that line of work. But absent a job that requires a major presence here, those who have been at the political top are often surprised to find the Capitol — and the capital — don’t hold the same allure once they step down.

Plus, he said, there is no one to hang out with.

“Nobody lives here anymore,” said Mr. Reid, who served as both the majority and minority leader. “When I came here, people lived here, they had their families, but not anymore. It wasn’t that way before. We made friends not only of the members, but of their families, their children. It is so changed.”

To get a last bit of that old-home feel, Mr. Reid organized a luncheon on Thursday for about a dozen of his fellow former colleagues, at the MGM National Harbor casino resort outside the capital. It was a who’s who of former Senate Democrats, including Tom Daschle, Christopher J. Dodd, Blanche Lincoln, Mary Landrieu, Robert Torricelli, Ben Nelson, Joseph I. Lieberman, Paul Sarbanes, Ken Salazar, Max Baucus, Mark Pryor and Russ Feingold.