Joseph Lieberman of Connecticut retired from the United States Senate in 2013.

Since then, he’s been in and out of the news, both locally and nationally. Locally, Mr. Lieberman, a Democrat-turned-Independent (who caucused with the Democrats) who ran for vice president on the Democratic ticket in 2000 and has endorsed both Republican and Democratic presidential candidates (John McCain in 2008, Hillary Clinton in 2012,) and endorsed Josh Gottheimer, the freshman Democrat who represents the state’s Fifth Congressional district.

Like Mr. Gottheimer, Mr. Lieberman feels strongly that compromise is necessary; he’s a founder of the group called No Labels, which advocates bridge-building rather than burning.

Nationally, Mr. Lieberman was on the New York Times’ and the Washington Post’s front pages last weekend. That’s when his good friend Senator John McCain of Arizona, the Republican who is dying of brain cancer and looking back at his life with the freedom impending death gives him, said that he wishes he’d listened to his own heart and chosen Mr. Lieberman as his running mate in 2008.

Rabbi Menachem Genack of Englewood, who heads the Orthodox Union’s kashrut division, is another good friend of Mr. Lieberman’s; in fact, the two men study together every week, usually but not always by phone, and have done so for the last 25 years.

In fact, Rabbi Genack said, he has been in Mr. Lieberman’s office when Mr. McCain has called; although much of their conversations are serious, they also joke with each other, the way friends do. He remembers Mr. McCain joking with Mr. Lieberman about a ride in a Shabbes elevator they took together. They were going to a penthouse. It was a tall building, and a very long ride. Mr. McCain “said that it was an expletive-deleted funny experience,” Rabbi Genack reported. He also remembers an autographed picture that Mr. McCain sent Mr. Lieberman; on it, he’d scrawled “Joe, I miss you in the Senate — but I don’t miss the salmon!” (That’s what Mr. Lieberman would eat.)

On Sunday, April 29, Rabbi Genack and Mr. Lieberman were among the 2,000 or so Orthodox Jews who went to Citi Field, the Mets’ home stadium in Flushing Meadows, Queens, to listen to speakers and learn Torah. Rabbi Genack and Mr. Lieberman were learners, but they also were teachers; they shared a session where Rabbi Genack interviewed Mr. Lieberman about his new book, “With Liberty and Justice.”

Torah in the City, now two years old, is a full-day program of plenaries and (slightly, but still very big) concurrent shiurim, taught by Orthodox luminaries for the Orthodox Union, starting with daf yomi at 8:45 in the morning and concluding at 6. Citi Field is an easy place to get to — it’s the center of a tangle of subways, trains, and highways — and there’s enough parking for a stadium full of fans (or students).

The program is all indoors, Rabbi Genack said; but “you are looking out over the field.”

The day is a project of OU’s president, Mark Bane, “who is very focused on getting people to study Torah,” Rabbi Genack said. To that end, “many of the issues discussed were contemporary issues.

“I went to hear Rabbi Yosef Tzvi Rimon talk about “The responsa that led to finding the three kidnapped boys from Gush Etzion,” Rabbi Genack said.

In 2014, three Israeli teenagers, Eyal Yifrah, Gilad Shaer, and Naftali Frenkel, were kidnapped; about three weeks later, their bodies were found. They had been murdered. “Rabbi Rimon is a rav in Eretz Yisrael” — he is an Israeli rabbi and scholar — “and he was one of the poskim” — the halachic decisors — “involved in finding their bodies,” he said. “The question was whether you are allowed to search for them on Shabbat, and the answer was yes.” If the search had not been allowed, he said, it is likely that their bodies would not have been found.

He also talked about listening to Sivan Rahav-Meir, a popular anchor on Israel’s Channel 2 who is a baalat teshuva, someone who had been just Jewish but returned — or just simply turned — to rigorous Orthodox practice. Ms. Rahav-Meir talked about interviewing Natan and Avital Sharansky, about how inspirational that is, and about how Mr. Sharansky said that in many ways “what people have to do now is more difficult than what he had to do then.” That, Rabbi Genack said, is because for him, “everything was black and white; he was fighting to leave a totalitarian regime, to be free.” Today, he said, often choices are not quite as stark, which makes them that much more difficult to make.

In his own session, Rabbi Genack and Mr. Lieberman talked about “With Liberty and Justice,” a book of 50 short chapters tracing the Israelites’ 50-day journey from Pesach to Sinai. It followed Mr. Lieberman’s “The Gift of Rest: Rediscovering the Beauty of the Sabbath.” “That book was very well received,” Rabbi Genack said. “I asked him why he didn’t write about Passover next, given that about 85 percent of American Jews make some kind of seder.

“He said no, he wanted to write about Shavuot, the most obscure, least observed of the holidays. He wanted to write about the links between the freedom of Pesach and the law at Shavuot, and about the journey from one to the other.” (Pesach is when the Israelites were liberated, and Shavuot is when God gave them the 10 Commandments and the rest of the law.) “He said he wanted to write about how the journey from Pesach to Shavuot, from freedom to law, has inspired the basic foundation of our democracy.

“The principles behind our Declaration of Independence are biblical principles,” Rabbi Genack said.

“We also talked about the corrosive environment nowadays, and what can be done about it,” he continued. “Joe represented bridge-building across the aisle, and in his last years in the Senate he was criticized for doing that.”

Still, both he and Mr. Lieberman have hope that the situation will change.