ALBANY – Kathleen Troia “KT” McFarland, a potential Republican challenger to Senator Clinton’s re-election bid, said yesterday she was physically abused as a child.

“Like too many Americans, I was raised in a household where physical abuse occurred,” Ms. McFarland said in a statement issued by her campaign. “It was something that left in me deep emotional scars, which I struggled to deal with for many years.”

Ms. McFarland’s spokesman, William O’Reilly, said the abuse came at the hands of her father and that one of her brothers, the late Michael Troia, also was abused.

A telephone message left for Ms. McFarland’s parents at their Wisconsin home yesterday was not immediately returned.

Polls show a tight race between Ms. McFarland and a former Yonkers mayor, John Spencer, for the GOP nomination to challenge Mrs. Clinton.

Ms. McFarland, a Reagan-era Pentagon official, said she was going public with the information because letters she had written to her parents as part of therapy had been obtained by members of the press.

“In seeking to put a painful past behind me, I wrote two candid letters to my parents in 1992 at the advice of a counselor,” her statement said. “Now, in the midst of a political campaign, those letters have found their way into the hands of a magazine reporter.”

Mr. O’Reilly said New York magazine had obtained the letters. The New York Post reported yesterday the magazine was planning to report on them in an upcoming issue.

The letters, according to the Post, discuss Ms. McFarland’s concerns about her late brother’s gay lifestyle, among other things.

“She was concerned about reckless behavior,” Mr. O’Reilly said yesterday.

Mr. O’Reilly said Ms. McFarland and her brother became estranged over his lifestyle and had not reconciled by the time he died in 1995. Mr. O’Reilly said Michael Troia was HIV positive and died from complications associated with the infection.

“I understand that, as a candidate for the Senate, my personal life is considered fair game,” Ms. McFarland, a political novice, said in her statement. “But my brother Mike’s should not be. Mike passed away in 1995 and his choice of lifestyle and the abuse he suffered as a child was not something he chose to make public while he was alive. I respectfully request that his memory remain private to all those who loved him.”

Mr. O’Reilly said Ms. McFarland “believed her father’s physical abuse contributed to her brother’s high-risk lifestyle, which was very painful for her to watch.”

Ms. McFarland delivered the letters in 1992 to her parents, Mr. O’Reilly said. The campaign spokesman said he had no details about the encounter.

Mr. O’Reilly said Ms. McFarland was in England yesterday for a reunion with fellow Oxford University classmates and unavailable for comment.

“She has since reconciled with her mother,” Mr. O’Reilly said.

Asked about relations between the candidate and her father, Mr. O’Reilly would only say, “She called her father on Father’s Day. They have occasional and cordial conversations.”

Mr. O’Reilly said no charges were ever filed against Ms. McFarland’s father.

In her statement, Ms. McFarland called on victims of child abuse to seek help.

“It is a tragedy that plays out every day behind closed doors, often in silence, many times in denial,” she said. “It places enormous strain on family relationships. A number of fine organizations now exist to help victims of domestic violence, and I urge anyone struggling with its aftereffects to seek them out.”

Ms. McFarland put links to support groups on her campaign Web site: http://www.ktforsenate.com

Asked about the possible political implications, Mr. O’Reilly said: “We will ask New Yorkers for understanding. Child abuse is a difficult and complex topic, but New Yorkers have a deep capacity for compassion in matters like this.”

Aides to both Mr. Spencer and Mrs. Clinton declined to comment.