Democrats will suffer politically if the battle over the nomination of U.S. Appeals Court Judge Robert H. Bork to the Supreme Court is seen as hinging on Bork's views on abortion or any other single issue, Senate Judiciary Committee Chairman Joseph R. Biden Jr. (D-Del.) said yesterday.

Biden, a candidate for the 1988 Democratic presidential nomination, reiterated his opposition to Bork in his strongest terms to date but warned that Democrats risk being portrayed as "a special-interest, single-interest vehicle" unless they mount a broad assault on Bork's fitness to succeed retired Justice Lewis F. Powell Jr. on the high court.

"I don't have an open mind" on the Bork nomination, Biden told a luncheon meeting with reporters. "The reason I don't have an open mind is because I know this man . . . . I see no way, based on my knowledge of Bork's record, that I could vote for Bork."

Because of these views, Biden added, "it seems to me it would be dishonest" not to make his opposition to Bork clear from the outset.

The "special-interest" label that has haunted Democrats in recent elections could be a particular problem for Biden as he seeks a delicate balance between his dual roles as Judiciary Committee chairman and presidential aspirant. It has already forced him to defend, as he did yesterday, his decision to announce his opposition to Bork weeks before the scheduled beginning of hearings on the nomination Sept. 15.

Biden expressed "serious doubts" about Bork the day President Reagan nominated him. A week later, he met with a group of civil rights leaders and other liberal activists and pledged to lead the fight against the nomination. The same day, Biden publicly announced there was "an overwhelming prospect" that he would vote against Bork.

But last Saturday, speaking to the Association of State Democratic Chairs in Cleveland, Biden said he "made a mistake" in publicly opposing Bork this early in the confirmation process.

Biden said yesterday that his only regret concerned the timing of his statements on Bork. "It was more of a public-relations mistake than a substantive mistake," he said.

He said he was familiar with Bork's views from studying his writings and from reviews of Bork's record that were prompted by speculation that he was in line to fill earlier Supreme Court vacancies.

"If Bork is what he has written for 35 years, I can't be for him," Biden said.

Among Bork's most controversial views is a statement that the Supreme Court's 1973 decision legalizing abortion was "unconstitutional." Numerous "pro choice" groups have vowed an all-out fight against Bork's nomination, but Biden warned yesterday that "it will be damaging if it comes down to a single issue."

Biden also held out the possibility that the Bork nomination could be killed in the Judiciary Committee, which is sharply divided along ideological lines. He said that if the committee votes against Bork he will "strongly recommend" that Reagan withdraw the nomination.

However, this scenerio appears unlikely. Both Biden and Senate Majority Leader Robert C. Byrd (D-W.Va.) have said repeatedly that the nomination should be decided by the "full Senate."

Biden said he agrees with Senate Minority Leader Robert J. Dole (R-Kan.) that the Senate is closely divided on the nomination, with the outcome depending on about 15 "swing votes." He said he was "reserving judgment" on whether he would lead a filibuster against the nomination.

Biden is scheduled to deliver a major speech on the Senate floor today on the Senate's role in confirming Supreme Court nominees. It is expected to be the first in a series of speeches detailing his opposition to Bork as Reagan's chosen "vehicle" to advance a conservative social agenda.

As Biden was speaking to reporters yesterday, another Judiciary Committee member and Democratic presidential contender, Sen. Paul Simon (D-Ill.), was also defending the Senate's right to subject Bork and his views to close examination.

"The Senate is broadly representative of the country's political diversity," Simon said. "It does not defer to the president when it thinks his proposed budget or legislation will harm the country, and the same should be true with respect to his judicial nominees."

Simon made the remarks in a speech prepared for the Washington Council of Lawyers. He distributed the speech text, but then spoke informally about the qualifications of a Supreme Court nominee, including that he be "someone of balance and sensitivity."

"I assume a Ronald Reagan nominee will be a conservative," Simon said. "Justice Powell was a conservative, but he was a man of balance and sensitivity."

Simon said he wants to be sure that Bork has "an openmindedness," a "sensitivity to civil rights . . . civil liberties {and} to separation of powers."

Simon said he will not decide his vote on Bork until after the hearings, but added, "I have serious reservations on the balance and sensitivity issues. The law shouldn't be a pendulum that swings back and forth according to who is president."