They write confidential reports summarizing their research and recommending a rating of “not qualified,” “qualified” or “well qualified” to the full panel, which then votes. In the event of conflicts of interest, evaluators are to recuse themselves. If an evaluator intends to recommend a “not qualified” rating, the White House may ask the head of the panel to appoint a different evaluator to take a second look.

The committee does not disclose its ratings of judicial prospects unless the president goes on to nominate them. In cases where presidents have nominated people who were rated “not qualified,” the panel chairman has traditionally testified about its concerns at their confirmation hearings.

To protect the confidentiality of people interviewed about the candidate, the committee often identifies only general categories of concern. According to a person familiar with the ratings, in discussions with the administration, the panel cited concerns about experience for six of the 14 candidates found “not qualified.” It also cited concerns over temperament for five, competence for three and ethics for three. (Three potential nominees were said to have been criticized as falling short in more than one of those areas.)

All but one of the 14 were being considered as district court judges, and — as is traditional — had been recommended for the Obama administration by members of Congress. One had been identified by the administration and was considered for an appeals court.

Officials of Mr. Obama’s legal team have met several times with the chairman of the bar association panel over the last year to raise concerns over the number of negative ratings, and have raised the possibility that the panel’s emphasis on trial experience may have a disparate impact on female and minority lawyers because they may have been less likely to become litigators.

In April, for example, the panel chairman at the time, Benjamin H. Hill III of Florida, met at the White House with Mr. Obama’s counsel at the time, Robert Bauer. And in August, the White House lawyer with primary responsibility for judicial selection, Christopher Kang, and the assistant attorney general for legal policy, Christopher Schroeder, traveled to Toronto for discussions with Mr. Joseph at the bar association’s annual meeting, officials said.

The committee has been more likely to deliver a harsh verdict about Mr. Obama’s prospects than it was during either the Clinton or Bush administrations. It has rejected about 7.5 percent of his prospects, compared with about 2 percent of the potential judges under each of the two previous presidents.