Former president Gerald R. Ford will introduce and endorse Judge Robert H. Bork before the Senate Judiciary Committee today as the panel formally begins what is expected to be a long and bitter battle over Bork's nomination to the Supreme Court.

Ford's appearance, in an unprecedented role for a former president, is expected to underscore the high political stakes each side sees in the outcome of the confirmation fight.

On the eve of the hearings, which begin at 10 a.m. today, a senior adviser to Committee Chairman Joseph R. Biden Jr. (D-Del.) said Democratic opponents of the nomination plan a broad assault on Bork's overall judicial philosophy and "the implications for the future" should he be confirmed.

The focus of the hearings will be "the broad-ranging constitutional philosophy by Bork that does not reflect the American people," the adviser said.

Bork's opponents also hope to raise questions about his views on civil rights and other issues important to Democratic senators from the South, where people "don't want to reopen issues they fought so hard to settle," the Biden adviser said.

Bork's supporters are counting heavily on the nominee's acknowledged intellectual abilities and personal charm to defuse the attacks.

A pro-Bork lobbyist said yesterday that the 60-year-old judge on the U.S. Court of Appeals here will begin his testimony with a statement, about five minutes long, designed "to show that he's human and not who he has been painted as by both sides."

"The right wing is jumping up and down saying he's one of ours, and the left wing is saying he's a right-wing kook," the lobbyist said. "We want to say he's a human being. Finally, we get to meet Bob Bork."

Bork also will be accompanied to the hearings by Senate Minority Leader Robert J. Dole (R-Kan.), Sen. John C. Danforth (R-Mo.), who studied under Bork at Yale Law School, and Hamilton Fish Jr. (N.Y.), ranking Republican on the House Judiciary Committee.

Ford's name headed the list of witnesses scheduled to appear before the committee this week. The hearings are expected to continue until about Oct. 1, when Biden has tentatively scheduled a committee vote on the nomination.

Aides to Sen. Strom Thurmond (S.C.), ranking Republican on the committee, said Bork will be supported during the hearings by former chief justice Warren E. Burger; Lloyd N. Cutler, White House counsel to Jimmy Carter; Illinois Gov. James R. Thompson (R), a former prosecutor; six former U.S. attorneys general; a dozen state and local law enforcement officials, and numerous academic and legal experts.

However, Bork himself will be the star witness as he seeks to rebut charges by critics that he is an extreme conservative whose confirmation would shift the closely divided Supreme Court sharply to the right.

In final skirmishing yesterday before the hearings, President Reagan said Bork's judicial philosophy "shouldn't be controversial in our democracy . . . and I hope it will be fully debated in the weeks ahead."

Reagan added: "I say I hope because, too often, character assassination has replaced debate on principle here in Washington. Destroy someone's reputation, and you don't have to talk about what he stands for."

Liberal and conservative groups went into high gear yesterday in their bitter and expensive battle over the nomination, holding news conferences to rebut each others' arguments and announce more studies of Bork's record.

The American Civil Liberties Union attacked a Justice Department report on Bork as a "misleading effort to divert attention from his radical philosophy."

People for the American Way, a liberal organization, launched a $2 million media campaign against the nomination, using television, radio and newspaper advertisements to argue that Bork's views "are so extreme that over the last 25 years he has consistently taken positions against the constitutional rights of all Americans."

The NAACP Legal Defense and Educational Fund Inc. joined People for the American Way in issuing a study arguing that Bork, since he became a federal appeals court judge in 1982, has stepped up his denunciations of Supreme Court rulings.

The study emphasized the recent vintage of Bork's statements because "he now tries to dismiss many of his more inflammatory statements as the musings of an academic," said John H. Buchanan, chairman of People for the American Way.

Bork's defenders in the administration and conservative groups also are promoting media campaigns and studies.

The Center for Judicial Studies, a conservative group, issued a report yesterday saying that Bork is not a "judicial activist" poised to push the Supreme Court to the right.

The study emphasized that he has often joined decisions not in keeping with his conservative political philosophy.

Assistant Attorney General William Bradford Reynolds last week dismissed as "utter nonsense" liberals' allegations that Bork will dismantle civil rights protections.

Bork has denied that he is a "conservative activist." In a Time magazine interview published this week, Bork said that "people on both sides are painting me as a conservative activist, predicting I'll do revolting or admirable things. It's not true. I simply believe in judicial restraint."