Alan Diamonstein, a power broker in the Virginia Democratic Party who represented Newport News in the House of Delegates for 34 years and championed greater state investment in higher education, died Oct. 17 at his home in Newport News. He was 88.

The cause was a heart ailment, said a grandson, Ben Allen.

A confidant of governors, senators and even a president, Mr. Diamonstein was described as understatedly savvy and enviably connected. He was a successful commercial and real estate lawyer who blended Tidewater bonhomie with a ringmaster’s organizational skills, and he cultivated the financial resources and personal relationships to advance in state and national politics.

He served in the House of Delegates from 1968 to 2002, representing a district along the James River that included Fort Eustis and the Newport News shipyard. He preferred backroom negotiations to media interviews and steadily advanced to chair the Education and Appropriations committees, giving him leverage over policy as well as funding.

The Daily Press of Newport News once described him as “Mr. Inside, lobbing tennis balls with the state’s most powerful lobbyists, flying to be with his friend Bill Clinton on election night, playing host to state power brokers in his box at the presidential inaugural gala, squatting in duck blinds with millionaires who are building Virginia and deciding its future course.”

First elected to the state House on a promise to empty what he called “the dustbin of Virginia politics,” referring to the racist Byrd political machine and its resistance to desegregating schools, he helped prepare the way for moderate Democratic governors throughout the 1980s and early 1990s: Charles S. Robb, Gerald L. Baliles and L. Douglas Wilder, the last of whom became the country’s first popularly elected black governor.

Mr. Diamonstein chaired the state Democratic Party in the mid-1980s, around the same time he was elected to the executive committee of the Democratic National Committee and led its Southern bloc. He advocated a centrist brand of politics that presaged the rise of President Clinton, another moderate Southerner.

“He fit the changing Democratic Party almost perfectly,” said Larry J. Sabato, founder and director of the University of Virginia Center for Politics.

In Richmond, Mr. Diamonstein became known for soothing bruised egos in a party known for fierce rivalries and nasty feuds. In the early 1990s, he showed unbending loyalty to then-Sen. Robb, who saw his presidential ambitions plummet amid a sex, drug and wiretapping scandal. Robb stayed at Mr. Diamonstein’s home in Newport News during part of the ordeal.

On policy matters, Mr. Diamonstein left an enduring mark on the state’s higher education system. He backed legislation to allow the admission of undergraduate women to the flagship state university in Charlottesville (where he was an alumnus) and supported bills to increase funding for the public university system’s general operations and student aid.

He also helped create the Virginia Housing Development Authority to help low-income residents attain affordable housing and used his clout to place women and minorities on state boards and commissions. Admired for his pragmatic streak, Mr. Diamonstein was one of a handful of legislators who served on a powerful committee that helps resolve budget differences between the General Assembly’s two chambers.

“Alan’s one of these people [who] is a very good barometer on what will clearly fly, on what clearly won’t fly, and what the person might negotiate,” former attorney general Mary Sue Terry (D) once told the Daily Press.

Mr. Diamonstein’s dealmaking prowess allowed him to top off the pork barrel for his district, specifically funding the Mariners’ Museum and colleges such as Christopher Newport University.

With a reversal of Democratic fortunes and the GOP takeover of the General Assembly by the late 1990s, Mr. Diamonstein saw his previously unalloyed power weaken. He did not run for reelection in 2001, instead making an unsuccessful run against then-Richmond Mayor Tim Kaine (D) for lieutenant governor. He returned after that race to full-time law practice at his Newport News firm.

Alan Arnold Diamonstein was born in Hampton, Va., on Aug. 20, 1931 . His father owned a furniture store and later a telephone answering service. His mother was active in Jewish philanthropies and women’s groups.

A graduate of the old Augusta Military Academy near Staunton, Va., Mr. Diamonstein served in the Air Force during the Korean War. He received a bachelor’s degree in commerce from the University of Virginia in 1955 and graduated from its law school in 1958. (He later served on the university’s Board of Visitors.)

His first marriage, to Barbaralee Dworkin, ended in divorce. In 1972, he married Beverly Hicks. In addition to his wife, of Newport News, survivors include four stepchildren, Candice Trusty of Miami, Trey Diamonstein of Hampton and Karen Allen and Kevin Diamonstein, both of Newport News; a sister; and five grandchildren.

Mr. Diamonstein was generally reluctant to draw attention to himself, but he occasionally allowed a glimmer of his diffident charm to shine through in an interview.

To the Daily Press, he recalled the time the film company making “Giant” (1956) — a big-budget production starring Elizabeth Taylor, Rock Hudson and James Dean — came to Charlottesville to hire extras for crowd sequences filmed in Virginia.

Mr. Diamonstein agreed to participate and, by his account, for a few weeks did little more than unobtrusively fill screen space — only to have his scenes scissored out in the final cut. But when he returned to campus on a bus with some of the cast, he shared in the hollers of enthusiasm from autograph seekers.

“Elizabeth Taylor would sign some . . . and Rock Hudson would sign some, and they’d come to me, and I’d sign some,” Mr. Diamonstein said. “Could you imagine a kid getting home and saying, ‘Alan Diamonstein?’ ”