Updated

Bernadine Healy, president of the American Red Cross, announced her resignation Friday, saying she was pressured to step down due to policy differences with her board.

Asked why she was leaving after just two years and so soon after the Sept. 11 terrorist attacks, she said, "I had no choice."

Healy said some of the policy differences had to do with how the organization should handle a decision by the International Red Cross to exclude the Israeli branch from membership. She said there were also disagreements over how to use nearly $500 million collected to aid victims of the Sept. 11 terrorist attacks.

"The board felt I was out ahead of them making policy," she told reporters at a news conference. "They didn't have any more confidence in me."

David McLaughlin, chairman of the Red Cross board, said the board did not force Healy to resign. Healy, standing beside McLaughlin, responded, "I don't think that's true."

Healy, 57, is one of only two physicians to head the charity. She said she would leave Dec. 31, but did not announce any plan beyond that.

Speaking to a ballroom filled with staff and volunteers, Healy said it was difficult to leave.

"Now seems right for new challenges in my own career," she said.

She defended her decision to keep money raised in the aftermath of the terror attacks separate from other Red Cross donations. "I strongly oppose commingling of the moneys with any other Red Cross disaster funds," she said, adding, "Reasonable people can differ."

Healy also called her response to the Israel issue – a decision to withhold administrative dues to the Red Cross' parent in Geneva – a "controversial but principled stand."

"This policy is now up for grabs," she said. "Reasonable people have differed with me on this and certainly other matters."

Healy succeeded Elizabeth Dole as president of the nation's largest charity on Sept. 1, 1999.

In the days following the Sept. 11 tragedy, Healy was often in the public eye. She appeared by President Bush’s side at the White House and on televised public-service announcements urging Americans to donate blood or money.

Healy rankled other charities collecting money for terror victims by refusing to go along with a coordinated effort led by the New York attorney general to keep track of how much money was being given to each family.

Many blood experts maintained it was wrong to encourage blood donations when they were not needed to treat victims of the terrorist attacks. Critics worried that excess donated blood would force the Red Cross to discard blood that expired before it could be used.

This week, the Red Cross acknowledged that about 4.5 percent of the red blood cells collected on Sept. 11 just expired, and 6 percent collected on Sept. 12 was expected to expire. Typically, 2.5 percent of red blood cells expire 42 days after they are collected. But Red Cross officials insisted that no one's donation went to waste because plasma and other products besides red blood cells were used.

Healy's time with the Red Cross has been scarred by controversy surrounding policies over who can donate blood and what measures must be taken to ensure its safety.

She was unable to free the organization from a court-ordered consent decree with the Food and Drug Administration over repeated violations of blood safety rules. Although the consent decree was in place when Healy took over the Red Cross, the FDA fight has escalated in recent months as the agency attempted to charge the Red Cross millions of dollars in fines.

She also took on the FDA last summer by pushing to restrict blood donations from anyone who had made even brief visits to Britain and Europe for fear of mad cow disease.

Healy is a former director of the National Institutes of Health, where she was a strong advocate on women's health issues, and former dean of the Ohio State University medical school. She also unsuccessfully sought the Republican Senate nomination in Ohio.

A native of Queens, N.Y., Healy earned her bachelor's degree from Vassar College in 1965 and graduated from the Harvard School of Medicine in 1970.

She completed postgraduate work at the Johns Hopkins University School of Medicine and served on the Hopkins faculty from 1976 to 1984.

President Reagan chose Healy in 1984 to be deputy director of the White House Office of Science and Technology Policy. From 1985 to 1991, she was chairwoman of the Cleveland Clinic Foundation.

She headed the National Institutes of Health from 1991 to 1993 before returning to Cleveland, where her husband, Dr. Floyd Loop, is chief executive officer of the Cleveland Clinic.

The Associated Press contributed to this report.