awrence Fuchs of Weston wrote ''the book'' on the political behavior of American Jews.
But yesterday Fuchs, a veteran Democratic activist and Brandeis professor, said he was surprised by Vice President Al Gore's choice of US Senator Joseph I. Lieberman of Connecticut as a running mate.
''If you had asked me who'd be the first Jew on a national ticket, I would have said a highly assimilated one, not an Orthodox Jew,'' said Fuchs, who wrote ''The Political Behavior of American Jews'' in 1956. ''Usually, you don't crack through with a seriously religious person.''
Jews and non-Jews from around the region yesterday reacted favorably to the decision, noting the political appeal for Gore of a running mate with a reputation for moral rectitude and high ethical standards.
Others, however, saw historical significance in the choice of the nation's first Jewish vice presidential candidate - coming as it does on the 40th anniversary of the Democrats' nomination of John F. Kennedy, also in Los Angeles, who would become the nation's first (and only) Catholic president.
''This has transcendent meaning for the Jewish community,'' said Barry Shrage of Newton, president of Combined Jewish Philanthropies of Greater Boston.
Philip Perlmutter of Newton, the author of ''Legacy of Hate,'' a book on the history of anti-Semitism in America, said Gore's choice shows that respect for religious diversity in America is growing.
''I'm delighted for him and for the country,'' said Perlmutter, the former director of the Jewish Community Relations Council of Greater Boston. ''Who could have predicted just a few years ago that they would take a Jew on a national ticket, and an observant one. But why not? Bush is running as a devout Christian.''
Lieberman and his wife, Hadassah Freilich, who grew up in Gardner, Mass., are Orthodox Jews who observe the Jewish Sabbath from sundown Friday to sundown Saturday.
Freilich, his second wife, was born in Prague in 1948 and moved to Gardner when she was 3, according to a spokesman for the senator. She graduated from Boston University in 1970 and has a master's degree in health care administration.
Many observers suggested that Lieberman's religion would help Gore get a needed jolt of attention before the Democratic convention next week, but Fuchs, the Brandeis professor, urged caution.
''I don't think this is a bid for the Jewish vote,'' said Fuchs, noting that the great majority of America's more than 5 million Jews already vote Democratic.
''It's about the fact that Lieberman is Mr. Ethics, the conscience of the Senate, a man whose morality and piety are without compromise,'' said Fuchs, who was an aide to President Kennedy.
Choosing Lieberman, he said, was a way for Gore to ''declare his independence from the more tawdry aspects of the Clinton presidency.''
However, Shrage, the head of Combined Jewish Philanthropies, said it would be hard to overplay the significance for American Jews.
''For us, it's a symbol of just what an amazing country America has been for the Jewish people,'' said Shrage, a second-generation American whose grandparents were born in the Ukraine.
Newton Mayor David Cohen also praised Gore's decision, calling it a ''bold and inspired choice'' that would invigorate his campaign.
Cohen was asked whether the 90 percent of American Jews who are either Reformist or Conservative would be uncomfortable with an Orthodox candidate.
''I think people all over the country are going to be impressed that Joe Lieberman is a man of deep faith, moral conviction, and unquestioned integrity,'' he said.
