DENVER -- Marty Mankamyer was accustomed to the power struggles within the U.S. Olympic Committee. The infighting became too much to take when the finger was pointed at her.

Mankamyer resigned as USOC president Tuesday night after colleagues blamed her for further fracturing the world's most powerful national Olympic committee.

The USOC's highest-ranking volunteer e-mailed her resignation to members of the organization's executive committee. Mankamyer said she doesn't have the energy to continue the job she took just 10 months ago.

"Because there appeared to be no possibility for peace unless I stepped aside, and with the thought that my action could make a positive difference for an organization to which I have devoted almost 20 years, I have decided to resign,'' Mankamyer said in her statement. "I wish the USOC the very best for the future.''

The 69-year-old Mankamyer had been pressured to resign after she was accused of working behind the scenes to oust chief executive Lloyd Ward.

Mankamyer resigned the same day The Denver Post reported that when she was a USOC vice president, she demanded a partial commission from a real estate agent who sold a $475,000 property to Ward when he became CEO in 2001.

Hours before she resigned, Mankamyer told the newspaper she was rightfully owed a "referral fee'' from Ward's house purchase because she showed apartments to Ward's wife in Colorado Springs. She said she was paid about $9,500.

Brigette Ruskin told the Post that Mankamyer sent her a series of letters in November 2001 asking her to pay a referral fee for the property purchase. She also said Mankamyer told Ward to pressure her to pay the fee.

Such fees are common when one real estate agent refers business to another.

Ruskin would not release Mankamyer's letters but said she will give them to Congressional investigators if asked.

Former USOC ethics officer Pat Rodgers said he learned Mankamyer was showing properties to Ward while he was still a candidate for the CEO job and warned both of them that they should not do business with each other.

Under USOC bylaws, vice president-secretariat William Martin will serve as interim president. The USOC's board of directors will vote on a permanent replacement after a nomination by the executive committee.

The board of directors is to meet in April, but no election date has been set.

"We are greatly indebted to Marty for her many years of service to the USOC,'' vice president Herman Frazier said. "We look forward to continuing to focus on the mission of the USOC, to help U.S. Olympic athletes achieve sustained competitive excellence and to preserve and advance the Olympic ideal.''

"The IOC regrets very much the leadership crisis of the USOC and is clearly sad to learn of Mrs. Mankamyer's resignation,'' IOC president Jacques Rogge said Wednesday in a statement to The Associated Press.

He added that the IOC hopes for a "rapid resolution'' and does not want the USOC's problems to ``deflect from the important role of the USOC in the Olympic movement.''

The USOC's executive committee was expected to take a vote of no confidence this weekend in Chicago after seven members, including all five vice presidents, asked for her resignation.

The group claimed Mankamyer distorted facts in an ethics case against Ward in an attempt to gain power.

Ward was accused of trying to help a company with ties to his brother land a power deal with the 2003 Pan American Games. But the USOC's ethics committee gave him a light reprimand Jan. 13.

Mankamyer agreed to step down after Ward was cleared, then changed her mind after five USOC members resigned in protest over the Ward decision.

Mankamyer's decision to stay further split the already-fractured organization, with accusations and attempted coups escalating almost daily.

Mankamyer said she wouldn't resign even after Ward called for her to quit, but she finally gave in to the pressure on Tuesday.

"As much as I love the Olympic movement and amateur sports, I cannot in good conscience continue when I know how much additional time and energy will be required,'' said Mankamyer, who plans to remain on the board of directors.

The latest in a long line of scandals has drawn the attention of Congress.

USOC officials, including Ward and Mankamyer, were summoned to a Senate Commerce Committee hearing in Washington on Jan. 28 to discuss the future of the troubled organization.

The committee, led by Sen. John McCain, R-Ariz., criticized the USOC for its incessant infighting almost since it was created in 1978.

The USOC has had three presidents in two years and three CEOs since 2000. Mankamyer's predecessor, Sandy Baldwin, resigned in April after eight months on the job, admitting she lied about her academic credentials.

"This is a time when the USOC needs to refocus on its priorities and avoid public displays of disagreement,'' said Mankamyer, who served as interim president before being approved by the USOC board of directors on Aug. 15.

McCain and Alaska Sen. Ted Stevens, who helped create the act that chartered the USOC 25 years ago, want a mechanism to settle conflicts among staffers and volunteer leaders on the 123-member board of directors.

McCain plans to meet with USOC officials and athletes at the Olympic Training Center in Colorado Springs this month, and a second Senate hearing is in the works.

"I think the passage of time eroded the basic environment that the USOC was born in, and it's time to take another look,'' Stevens said at the committee hearing Jan. 28. "I think we need to get a greater command-and-control mechanism in the USOC.''

Norm Blake, Ward's predecessor, lasted just nine months before resigning in 2000 amid internal strife. Ward became the USOC's 12th CEO in 25 years following a yearlong search that ended in October 2001.

In 1991, president Robert Helmick became the first IOC member to resign under pressure after he was accused of using his position for personal gain.

USOC official Alfredo La Mont stepped down in 1999 after revealing a business relationship with a former member of the Salt Lake Organizing Committee. The USOC also was tarnished by the Salt Lake City bribery scandal.

"Scandal seems to follow the USOC like dogs following a meat wagon,'' Sen. Ron Wyden, D-Ore., said at the committee meeting.