A razor-thin majority of Virginia's House of Delegates rejected a tougher seat belt law today, reversing the vote it took a day earlier and ending a month-long debate with Gov. Mark R. Warner (D) about road safety versus personal liberty.

Warner had said Virginia police should be allowed to stop and ticket adults for failing to buckle up without first noticing another offense. Proponents say that making the failure to use a seat belt a primary, rather than secondary, offense would save more than 100 lives each year and prevent thousands of injuries on the state's highways.

But opponents, including most of the House Republican leadership, cast the issue as one of protecting an individual's right to be left alone. They said the proposed seat belt law was intrusive and would grant the government too much control over personal decisions.

"Our heritage is not to restrain people's freedoms, but to preserve them," said Majority Leader H. Morgan Griffith (R-Salem). "There is a streak of defenders of liberty -- that philosophy -- in the House."

Warner, who repeatedly lobbied Democratic lawmakers to get the bill through unfriendly committees and onto the House floor, issued a statement today expressing disappointment.

"A primary seat belt proposal was first introduced in the General Assembly in 1972," Warner noted. "This proposal will continue to have my support until it is allowed to become law. It is the right thing to do."

Angry Democrats and road safety advocates accused Republicans of killing the measure rather than allow Warner to succeed on one of his priority bills.

"This was political expediency over personal conscience," said House Democratic Caucus Chairman Brian J. Moran (Alexandria). "This was going to be portrayed as a Warner victory. For that reason, it drew more opposition than it should have. They didn't want to provide the governor a victory in this regard."

For a brief time, it seemed as though advocates had finally won after years of trying to get a primary seat belt law passed. Thursday night, the measure passed the House 49 to 48. The Senate had already passed the bill, and Warner was eager to sign it.

But this morning, opponents used a parliamentary maneuver to reconsider the vote. After a brief debate, delegates voted again. This time, after a night of intense lobbying on both sides, the electronic board that tallies the votes showed 48 to 49.

"Yesterday, they voted for this. Now they do the opposite," said a sobbing Patty French, a Stafford woman whose son was killed in an automobile crash in which he wasn't wearing his seat belt. "How can they do something like this? This is totally out of control."

Three Republicans who voted for the seat belt law Thursday night, including Majority Whip Jeannemarie A. Devolites (Fairfax), reversed themselves and voted against it this morning.

Devolites said she was "never comfortable" with the vote she took Thursday night and was convinced by today that a tougher law would give too much power to the police, who might abuse the law.

"I'm concerned about allowing law enforcement to look into our windows," Devolites said. "If people aren't going to wear their seat belts, they aren't going to wear their seat belts. You have to ask the question how far should government go."

Del. Robert F. McDonnell (R-Virginia Beach), who is running for attorney general, also switched, as did Del. Charles W. Carrico Sr. (R-Grayson), a former state trooper.

Carrico's vote was a surprise because he had said that his life was saved by a seat belt and that he recalled the victims who had been killed in automobile accidents. He said after the vote that he had received many calls from his constituents urging him to vote against the bill.

"I promised them it would not be my own personal feelings injected into this bill," Carrico said, calling the decision "the hardest thing I've ever had to do."

David Kelly, a spokesman for the Virginia Coalition for Child Safety, accused the Republican leadership of pressuring the three to switch.

"You really wish that people would have some guts to stand by their votes," Kelly said. "Did Delegate Carrico forget the names of the people he picked up off the streets, like he testified in committee?"

But Republicans were not the only ones to vote against the measure.

Several Democrats, including Del. Kenneth R. Melvin (Portsmouth), broke ranks with Warner and their party to oppose it. Melvin, a member of the Black Caucus in the House, said he thought passing the bill would give police officers another excuse to stop young black men without cause.

Melvin said he expected his vote to be cast as an anti-Warner message because the debate has become "all about politics and not policy."

"The governor's staff is not serving him well when a seat belt bill becomes a primary piece of legislation for the governor of Virginia," Melvin said. Explaining his vote, he said: "You have knuckleheads out there on these police squads. And those are the people I'm afraid of."

Staff writer R.H. Melton contributed to this report.

Del. H. Morgan Griffith, speaking, and Del. John A. "Jack" Rollison's III. Griffith said, "Our heritage is not to restrain people's freedoms."Majority Leader H. Morgan Griffith, shown with then-Speaker S. Vance Wilkins, opposed the measure.