Critics of the decision said they smelled politics at work.
Administration officials, lawmakers and interest groups that monitor the issue said Sunday they have been told the decision is final. One administration official, speaking on condition of anonymity, said an announcement is likely from the State Department on Tuesday, but added the timing could change.
White House officials said privately that conservative activists have for months quietly pressured the administration to prove President Bush's anti-abortion credentials by permanently denying money to the United Nations Population Fund. The fund helps countries deal with reproductive and sexual health, family planning and population strategy.
Conservative activists helped carry Bush to the presidency, and White House political advisers have carefully tended them with an eye to his re-election. But the decision on family planning could also damage Bush's standing with moderates and women.
The White House has kept the politically delicate decision a closely guarded secret. It has refused to divulge it even to allies in Congress, such as the Pro-life Caucus.
More than a dozen administration officials, inside the White House and out, declined to comment Sunday or did not return phone calls on the matter, so the reasoning behind the decision was not clear.
Just last year, Secretary of State Colin Powell told the Senate that the U.N. agency does ``invaluable work'' and ``provides critical population assistance to developing countries.''
Bush himself proposed $25 million for the organization, an increase from the $21.5 million the fund got during the last year of the Clinton administration. Key lawmakers later agreed on $34 million for the agency.
Two administration officials said Bush is now likely to channel the $34 million to family planning organizations run by the State Department's Agency for International Development.
A study from a U.S. government fact-finding mission to China in early May reportedly found no evidence that the U.N.'s program directly or indirectly facilitates forced sterilizations and abortions in China. A British delegation visited China a month before the U.S. team arrived and its investigators also did not find evidence that U.N. funds were misused for such purposes.
Bush sent $600,000 to the U.N. fund in November for humanitarian relief in Afghanistan. The money has been used to provide sanitary napkins to Afghan women and medical assistance with labor and delivery, officials said.
In advance of the administration's formal announcement, 48 members of Congress asked Bush last week to explain why he had withheld the $34 million after approving it in January.
The lawmakers said they wanted to ``share our understanding'' of how U.N. Population Fund programs in China operate. They also asked the president to release the report from the U.S. fact-finding mission to China.
White House spokesman Scott McClellan promised last week that the administration will release the report when Bush's decision on the U.N. money is formally announced.
Critics of the decision said it was driven by politics.
Rep. Carolyn Maloney, D-N.Y., attributed it to the White House's ``mindless zeal to take care of their right-wing base.''
But Deal Hudson, editor of the Roman Catholic magazine Crisis, praised Bush's move.
"My information is that it's permanently withheld, and that's good news to people who think like I do,'' Hudson said. ``The U.N. population fund is bad policy because it relies on population control rather than economic development to address problems of poverty; and the problem is not population, the problem is underdevelopment.''