More than two dozen progressive groups, led by Naral Pro-Choice America, submitted a letter opposing the nomination of Mr. Boggs, and some Democrats on the Judiciary Committee are already questioning the nomination, raising the possibility that one of Mr. Obama’s judicial choices could be rejected by his own party.

“I am strongly considering whether he should be withdrawn because I have very serious concerns about some of the really unwise and inappropriate views he has stated,” said Senator Richard Blumenthal, a Connecticut Democrat who sits on the judiciary panel. “As a starter, I want to have some conversations with the White House and determine what they were thinking.”

Other Democrats on the committee said they had just begun to review the nominations. Senator Patrick J. Leahy, the Vermont Democrat who leads the committee, said he intended to schedule confirmation hearings once the necessary reports were in hand.

“If the president sends up a nominee, they ought to at least get a hearing, and we will see where we go from there,” said Mr. Leahy, who said he has made no decision on the nominations.

“I am not committed one way or the other,” he said. “The deal is with the president, not me.”

Administration officials countered the criticism, noting that Mr. Cohen was asked to lead the defense of the voter identification law by the Democratic attorney general of Georgia. In the case of Mr. Boggs, White House officials said that he had built a wide reputation for fairness and openness in his decade on the bench and has a special expertise in criminal sentencing reform, a subject of significant interest to the president.

“None of the criticisms, nothing is based on his record as a judge for 10 years,” said Kathryn Ruemmler, the White House counsel. “What has distinguished him as a state court judge at the trial level as well as on the court of appeals is he has taken a keen interest and leading role in criminal justice reform.”

Senator Chambliss also dismissed the criticism of Mr. Boggs. “These objections that are being raised are pretty baseless,” he said, challenging the groups to find a biased ruling by Mr. Boggs.