ASHINGTON, Aug. 2 — The Senate Commerce Committee voted today along party lines to reject President Bush's choice to head the Consumer Product Safety Commission, handing him his first nomination loss.

By a vote of 12 to 11, Democrats rebuffed the nomination of Mary Sheila Gall, saying her record as a member of the commission showed an alarming disregard for children's safety and warning that her elevation to chairwoman would benefit manufacturers, not consumers. They expressed particular concern about her reluctance to push for federal oversight of faulty baby walkers, baby bathtubs and bunk beds. Thousands of children were injured by the products and some killed.

Ms. Gall told the senators last week that she sought to curtail the government's reach when other solutions seemed appropriate. She said she did not think much progress could be gained by regulators who "club people over the head."

For months Republicans had predicted their first big confrontation with Democrats over nominations would relate to judges. Instead, Democrats chose Ms. Gall, an obscure member of a commission that typically attracts little attention, but one whose track record they said made the Bush administration seem callous about children's safety.

The product safety commission sets safety standards and orders recalls of products that could cause death or injury.

Another Bush nominee, Robert S. Mueller III, was unanimously endorsed by the Senate Judiciary Committee today to become director of the Federal Bureau of Investigation. His confirmation by the full Senate is assured, probably this week.

On the safety commission nomination, Senator John Edwards, a North Carolina Democrat on the commerce panel and a personal injury lawyer, said that as chairwoman, Ms. Gall would have to serve as "chief advocate for those who simply cannot protect themselves."

"She has repeatedly opposed modest standards that would prevent injury, even when the standards were supported by industry," Mr. Edwards said. "Instead of trying to make products safer, she blames consumers, parents and caregivers."

Republicans immediately accused Democrats of playing partisan politics in rejecting a nominee who had twice been confirmed by the Senate to serve on the commission. Senator John McCain of Arizona, the ranking Republican on the committee, labeled it a "smear campaign."

Shortly after the vote, Senator Tom Daschle, the majority leader from South Dakota, all but doomed the nomination by ruling out a full Senate vote. "When the committee speaks on nominations, other than judicial, I think that ought to be the final word," Mr. Daschle said. "I don't have any expectation that it needs to go further than that."

But the White House and Republicans vowed today to explore ways to rescue Ms. Gall's nomination. One possibility was to persuade Mr. Daschle to change his mind. A Republican senator raised the possibility of stalling the Senate's work until Ms. Gall's nomination is taken up. The White House may also have the option of downgrading the current chairwoman, Ann Brown, a Democrat, to commissioner, to force action on the nomination. Ms. Gall is the only Republican on the three- member commission.

"Mary Gall did not lose today," said Ari Fleischer, the White House press secretary. "Bipartisanship lost today. Suffice it to say the president was disappointed in the vote."

Republicans expressed astonishment at the Democrats' action, calling it inexplicable considering that Ms. Gall had been renominated and confirmed in 1999 under President Clinton. President George Bush appointed Ms. Gall in 1991.

Senator Hillary Rodham Clinton, Democrat of New York, a friend of the current chairwoman, Ms. Brown, took a leading role in opposing Ms. Gall's nomination.

Senator McCain said that when Ms. Gall came to her confirmation hearing last week: "What she faced was a group of senators with rope in their hands. For partisan reasons, Ms. Gall was going to be hanged regardless of what she said."

But Democrats contend that Ms. Gall was reconfirmed in 1999 as part of a quid pro quo deal with Republicans that also cleared the way for Ms. Brown's confirmation as chairwoman. And they note that, as chairwoman, Ms. Gall would have considerably more power to set the agenda.

The Consumers' Union, which publishes Consumer Reports and typically does not make recommendations on nominations, took the unusual step of opposing her selection.

At a hearing before the committee last week, Ms. Gall faced an onslaught of difficult questions from Democrats about some of her votes.

In 1994, Ms. Gall voted against opening an investigation into a faulty brand of baby bath seat. Parents had complained that the seats easily tipped in the bathtub, leaving their children vulnerable to drowning.

At the hearing, Ms. Gall stated that in 1994 the commission faced "extreme cases" in making their decision. In one case, the mother was drunk, left the water running in the bathtub and failed to supervise the baby. "There is no mandatory standard, there is no performance standard, there is no bath that will protect the baby in that kind of circumstance," she said.

This year, Ms. Gall reversed her vote on the seats, saying new evidence showed there was a problem.

Another problematic vote for Democrats concerned Ms. Gall's reluctance in 1999 to require bunk bed manufacturers to repair a problem that had injured children by wedging them between slats. She was the lone dissenter that year when the commission voted, 2 to 1, to require mandatory safety regulations for bunk beds. Ms. Gall said she felt the manufacturer could voluntarily agree to fix the problem.

Consumer watchdogs said that 89 children had died and 31,000 had been injured as a result of the defect. This was over a period of 10 years.

"I am convinced that President Bush can do better," said Senator Ernest F. Hollings, the South Carolina Democrat who is chairman of the committee, before casting his vote.