Clinton Aides, Possible Court Nominee Meet : Law: U.S. Judge Stephen G. Breyer talks to officials in Boston hospital, where he was treated after a bicycle accident. Some groups voice concerns.

White House officials met Thursday with U.S. Appeals Court Judge Stephen G. Breyer in a Boston hospital room, signaling that the nearly three-month-long search for a new Supreme Court justice may be winding down.

Breyer, injured in a bicycling accident, was released Thursday night from Mount Auburn Hospital and will travel to Washington today for a face-to-face meeting with President Clinton, aides said.

The judge is now believed to have edged ahead of Interior Secretary Bruce Babbitt as the President’s choice to replace retiring Justice Byron R. White.

Other Administration sources, however, indicated that Clinton’s lengthy deliberations might not yet be over.

Some White House aides and environmental activists were expressing last-minute misgivings about whether Breyer’s views on certain issues are too conservative.

Some aides said Clinton is considering other candidates, including Judge Ruth Bader Ginsburg of the District of Columbia Circuit Court of Appeals.

Dee Dee Myers, Clinton’s press secretary, said Thursday that an announcement “could come as early as tomorrow. It could come later.”

The hospital visit by White House staff members was the final step in the investigation of Breyer, whose name has been under consideration since White announced on March 19 that he will retire. A staff study of Babbitt’s work and background is already completed.

One of Breyer’s advantages as a candidate is that the former counsel to the Senate Judiciary Committee has elicited little criticism and gotten support from both sides of the political spectrum.

Backers include conservatives such as former judge Robert H. Bork, whose nomination to the high court by former President Ronald Reagan was rejected, and Sen. Orrin G. Hatch (R-Utah) and liberal figures such as Sen. Edward M. Kennedy (D-Mass.) and Senate Judiciary Committee Chairman Joseph R. Biden Jr. (D-Del.).

But some White House aides were expressing the fears on Thursday that conservatives’ apparent efforts to steer Clinton from Babbitt to Breyer might be an indication that Breyer is more conservative than the Administration would like.

Breyer, an architect of airline deregulation, has voiced reservations about some kinds of antitrust enforcement and other government actions to regulate business.

Environmental groups also voiced concern about what some said is Breyer’s mixed record on environmental protection.

Breyer is about to publish a 112-page book, “Breaking the Vicious Cycle,” which details his argument that a substantial share of what the government spends on environmental protection is wasted.

In the book, he cites his own experience presiding over a case in which $9.3 million was spent to make a toxic dump a safe place for children to eat small amounts of dirt.

“But there were no dirt-eating children in the area,” Breyer wrote. “It was a swamp.”

Ronald J. Tipton, the National Audubon Society’s vice president for government affairs, said some of Breyer’s writings “would obviously raise concerns about how he might decide cases based on current government regulation.”

At the same time, he praised Breyer’s legal accomplishments and said environmentalists may agree with him in many areas.

Several environmental leaders said that while some groups might quietly share their concerns with the White House, they probably would not actively oppose Breyer.

They said that is partly because several environmental groups have already publicly opposed the selection of Babbitt, who they wish to remain as Interior secretary.

Babbitt’s prospects for the high court seat apparently declined this week because of those anxieties and White House concerns that his political skills in Western states would be lost in the 1996 election if he is on the court.