Three years after he reluctantly gave up the quiet life of an academic to accept the presidency of the Hebrew Union College-Jewish Institute of Religion, Rabbi David Ellenson has emerged as a strong leader, a tireless fund raiser and a powerful voice within Reform Judaism for the issues he has long championed, including traditionalism and interdenominational dialogue. Ellenson, 57, the eighth president in the college's 125-year history, has made priorities of strengthening the institution's ties to Israel and building the endowment. Raised in an Orthodox home in Virginia, ordained at HUC's New York school in 1977, Ellenson was known chiefly as a scholar of modern Jewish intellectual history, specializing in the development of religious denominationalism over the last two centuries. His expertise serves him well in his new job; he's on good terms with leaders of other movements, and he was the only non-Orthodox rabbi invited to address a recent conference of rabbis and Catholic cardinals. And research has not stopped. His latest book, After Emancipation: Jewish Religious Responses to Modernity, published by HUC, came out only a month ago.