BANGOR, Maine — President Barack Obama on Wednesday nominated Assistant U.S. Attorney Nancy Torresen to serve as a federal judge in Portland.

If confirmed by the U.S. Senate, Torresen, 51, of Bangor would replace U.S. District Judge D. Brock Hornby, who assumed senior status a year ago but plans to maintain a full caseload. She also would be the first woman to serve as a U.S. District judge in Maine, but not the first recommended for the job.

In April 2010, U.S. Reps. Mike Michaud and Chellie Pingree recommended Superior Court Justice Michaela Murphy, 55, of Rome for the job. Her nomination was never announced by the White House.

Last fall, Murphy withdrew her name from consideration due to “health and family reasons,” Mary Ann Lynch, spokeswoman for the state court system, said Thursday on the judge’s behalf.

Murphy is presiding this week over the murder trial of Zachary Carr at the Penboscot Judicial Center in Bangor.

Michaud and Pingree reacted to Obama’s nomination of Torresen in a press release issued Wednesday.

“The diverse screening panel we convened last year did a thorough job, and we’re pleased that the president has chosen one of the names we jointly forwarded to him for consideration,” they said in a joint statement. “The next federal judge will play an important role setting the tone and priorities of the federal judiciary in Maine. Nancy would bring a fresh perspective and a breadth of experience and knowledge from her diverse legal background to the federal bench in Maine.”

Efforts Thursday to reach Torresen were unsuccessful.

The Senate Judiciary Committee must now review the nomination and present a recommendation to the full Senate for approval.

Federal judges are appointed for life. The salary of a U.S. District Court judge in 2011 is $174,000 per year, according to information on the website for the federal court system.

How long it will take for Senators to vote on Torresen’s nomination depends on when the Senate Judiciary Committee schedules a hearing on her nomination. While some nominees to the U.S. Supreme Court and federal appellate courts have been controversial, nominees to the District Court bench have not been.

John Woodcock, now the U.S. District Court judge in Bangor, was nominated at the age of 52 by President George W. Bush in March 2003. Woodcock appeared before the Judiciary Committee two months later and was confirmed on June 12, 2003, by a Senate controlled by Democrats. He was sworn in and on the job two weeks later.

Torresen first  joined the United States Attorney’s Office in 1990, where she initially handled civil matters involving federal agencies. In 1994, Torresen was designated to the Appellate Section of the Criminal Division of the Maine Attorney General’s Office, where she was primarily responsible for representing the state in appeals of serious violent crime convictions.

In 2001, she returned to the U.S. Attorney’s Office and has been responsible for investigating and prosecuting federal crimes.

From 1988 to 1990, Torresen worked at the law firm of Williams & Connolly in Washington, D.C. She served as a law clerk to former U.S. District Judge Conrad K. Cyr from1987 to 1988.

Torresen received her law degree in 1987 from the University of Michigan Law School and her undergraduate degree in 1981 from Hope College in Holland, Mich.

She is married to attorney Jay McCloskey, who served as U.S. Attorney for Maine under President Bill Clinton. The couple live in Bangor.