The frequency with which the U.S. attorney in Brooklyn seeks the death penalty is emerging as an obstacle to her confirmation to the federal bench.

Although President Bush first nominated Roslynn Mauskopf to a district judgeship last year, her candidacy is languishing before the Senate Judiciary Committee. The delay is due to questions from Senator Feingold, a Democrat of Wisconsin, relating to the rise in federal death penalty cases in Brooklyn since Ms. Maukopf became U.S. attorney in 2002, letters between Ms. Mauskopf and Mr. Feingold show.

Mr. Feingold, who opposes the death penalty, wrote Ms. Mauskopf last week that answers she provided to his questions on her death penalty cases “will be of significant help to me as I determine whether I am able to support your nomination for a lifetime appointment as a U.S. district court judge.”

Earlier this year, prosecutors under Ms. Mauskopf secured the first federal death sentence in New York since the era of Ethel and Julius Rosenberg, who were executed more than 50 years ago. The defendant in the recent case, Ronell Wilson, murdered two undercover detectives.

Prosecutors under Ms. Mauskopf have sought the death penalty at trial in three other cases, but were rebuffed by juries. Ms. Mauskopf’s office has pending capital charges against eight other defendants. The trial of two of them, men accused of taking out insurance policies on alcoholics and then murdering them, opened yesterday.

In a letter dated April 30 responding to Mr. Feingold’s written questionnaire, Ms. Mauskopf said she never received “pressure or encouragement” from the Justice Department or Bush administration officials to pursue more death penalty cases. Ms. Mauskopf also wrote that her “office’s record of seeking the death penalty was never a topic of discussion” during interviews with Bush administration officials during interviews regarding whether she would be nominated.

Mr. Feingold, in a follow-up letter last week to Ms. Mauskopf, did not state whether he would support her nomination. He said he first required more information: what Ms. Mauskopf had recommended to the attorney general in the more than 100 instances in which her office had the choice to seek the death penalty.

The decision to pursue the federal death penalty is made by the attorney general, but local U.S. attorneys offer their recommendation in each case. The Justice Department closely guards that information, and Ms. Mauskopf earlier told Mr. Feingold that she is “not at liberty to disclose information concerning” her recommendations.

A spokesman for Ms. Mauskopf declined to comment.

In other news, the Senate yesterday unanimously confirmed a Columbia Law School professor, Debra Livingston, to a seat on the 2nd U.S. Circuit Court of Appeals, which sits in Manhattan.