The tumultuous 1968 convention is where I cost the Democrats the presidency. At least that’s what the press secretary for that year’s defeated Democratic nominee told me.

As a junior member of the Associated Press, I was assigned to wait outside the suite of the presidential nominee, Vice President Hubert Humphrey, as he finalized his choice of a running mate. At one point, press secretary Norman Sherman emerged to say Humphrey still was consulting leaders.

Did those leaders include Lyndon Johnson? I asked, innocently. Johnson was sulking at his Texas ranch, unwelcome at the convention after splitting the party and withdrawing from the race.

“Lyndon who?” replied Sherman. Quickly realizing his faux pas, he added, “That’s off the record.”

I looked at the three dozen reporters in the corridor and realized I couldn’t comply with Sherman’s request. When I reached a phone, I dictated the exchange, then resumed my wait. Eventually, Humphrey picked Maine Sen. Edmund Muskie, providing hope for a convention marked by bitterness inside and clashes between police and antiwar protesters outside.

Unknown to me, my AP colleague Harry Kelly advised Sherman I was going to file his snarky comment, which meant wide dissemination since the AP wire was the closest thing to today’s internet.

All hell broke loose at the Johnson ranch, I learned later when Sherman related the incident to Todd Purdum, who was writing a book about the 1964 Civil Rights Act.

“A Secret Service agent came up to me and said there was a call from ‘THE RANCH,’” Sherman recalled. Johnson’s press secretary, George Christian, and his deputy, Loyd Hackler, were on the phone, and “when I said hello, they shouted ‘Norman, who.’ We laughed and hung up.”

Sherman said Humphrey looked at him and “snarled, ‘Did some son of a bitch on our staff say, ‘Who’s Lyndon?’”

“You’ve got the right son of a bitch, but the wrong line. I said, ‘Lyndon who?’” Sherman replied.

Sherman later discovered Arthur Krim, Humphrey’s main fundraiser, called him from the ranch and said he wouldn’t raise a penny more “if he had people like me on the staff.”

For years, Sherman regularly but jocularly blamed me for costing Humphrey the election. Actually, Humphrey lost due to internal party divisions.

This incident is one of several memorable events I recall from Chicago where I covered the politics, not the daily clashes in the streets.

One was the year’s only presidential candidate debate, as Humphrey, Minnesota Sen. Eugene McCarthy and South Dakota Sen. George McGovern clashed before the California delegation.

Another was turmoil in the convention’s Rules Committee, which had a lasting impact. A floor fight which insurgents won led to creation of the McGovern Commission, which overhauled the party’s nominating procedures in a way that prompted most states to adopt primaries and scrap insider-controlled caucuses.

The Rules Committee met on an upper floor of the Conrad Hilton Hotel, and I noticed there were only two pay phones nearby. I was determined to ensure no one beat me on my piece of the story. An AP colleague, Austin Scott, had shown me how to make a pay phone inoperative by unscrewing the mouthpiece and turning over the diaphragm.

So that’s what I did, so I would have a phone when I needed one. Many tried unsuccessfully to use the doctored phone.

It always worked for me. At one point, I called my desk and was told The New York Times questioned my last update, since it had heard nothing similar from its correspondent.

“Maybe he’s having trouble finding a phone,” I said.

Democrats were so snakebit by that convention they avoided Chicago for the next 28 years. The 1996 convention that renominated President Bill Clinton ran smoothly, remembered mostly for the frequency delegates broke into “Macarena,” a popular song that summer.

Now, they are returning to Chicago, hoping for a convention more like 1996 than 1968. Though I won’t be there, I’ll be watching, as I bet will be an Iowa nonagenarian named Norman Sherman.

Humphrey died a decade later, having never reached the presidency. But we’re both still around to laugh about it.

Carl P. Leubsdorf is the former Washington bureau chief of the Dallas Morning News.