NEW YORK — Jewish leaders are joining Catholics in mourning the loss of New York's Cardinal John O'Connor, who died May 3 at the age of 80.

O'Connor was heralded as a man of conscience who helped improve Catholic-Jewish relations.

"He had the largest Jewish diocese in the world," said Rabbi Mordecai Waxman of Temple Israel in Great Neck, N.Y., a past leader of the International Jewish Committee for Interreligious Consultations.

O'Connor was known for his fierce opposition to anti-Semitism.

"No one who is truly Catholic can be an anti-Semite. It's a contradiction in terms," the cardinal said when awarded an honorary doctorate of humane letters by the Reform movement's Hebrew Union College – Jewish Institute of Religion, making him the first Catholic cardinal to be so honored by a Jewish seminary.

In line with those beliefs, O'Connor sent a letter last year to his Jewish friends before the High Holy Days expressing his remorse for violence committed against the Jews throughout the ages.

Though he omitted any direct reference to the Holocaust, Jewish leaders took his statement as a positive step toward bridging the gap between Catholics and Jews.

"I ask this Yom Kippur that you understand my own abject sorrow for any member of the Catholic Church, high or low, who may have harmed you or you forebears in any way," he wrote.

"The Jewish people lost a champion and I lost a friend," said Rabbi A. James Rudin, interreligious affairs director for the American Jewish Committee. Rudin said he was inspired when, inquiring about the cardinal's well-being, O'Connor replied, "Rabbi Jim, everyday is a holiday."

"He meant the joy of it all," Rudin said. "He loved being the cardinal."

Rudin also recognized O'Connor's role in matters concerning the Jewish state.

"I consider[ed] him a chief architect in establishing Vatican-Israel relations."

In 1987, O'Connor made a landmark visit to Jordan and Israel, where he provoked controversy following his endorsement of a Palestinian homeland and for acquiescing to a Vatican request that he downgrade meetings with Israeli officials.

The Conference of Presidents of Major American Jewish Organizations heavily criticized him, but the same group later acknowledged him for his role in urging the pope to grant political recognition to the Jewish state.

"He set the bar very high in terms of what should be done vis-à-vis Jews," Rudin said.

Though no one has been selected as O'Connor's successor, media reports have placed Bishop Edward Michael Egan of Bridgeport, Conn., at the top of the list.

Laurie Groff, a director at the Jewish Center for Community Services in the region served by Egan, said the bishop has attended several interfaith events when invited, and has often indicated "a desire to improve Catholic-Jewish relations," adding, "he is also aware and proud of the strides that have been made so far."

As a community leader, O'Connor was vocal in his support for labor and his opposition to abortion. He may also be remembered for his sense of humor.

Rabbi Aaron Landes of Beth Sholom Congregation in Elkins Park, Pa., who served as a Navy chaplain with O'Connor, recalls a trip they once took to Antarctica to visit sailors during Christmas.

"He regaled us with stories, especially about the seals," reminisced Landes, who laughed as he conjured up the image of the cardinal as he "acted out the parts of the seals."

Rabbi Marc Schneier, president of the North American Boards of Rabbis, will always remember one moment he shared with the cardinal.

Prior to being formalized as president of the New York Board of Rabbis in 1998, Schneier met with Pope John Paul II at the Vatican. Four days later, at his installation ceremony in New York where O'Connor served as the keynote speaker, Schneier addressed the cardinal and said, "The pope asked me to bring the cardinal blessings — under rabbinical supervision."

The cardinal, not to be out-joked, took the statement a step further. According to Schneier, "He stood and removed his red skull cap and placed it on my head."