This vote was on an amendment that would overturn a policy in place for most of the past 20 years that bars federal funds from going to any organization in a foreign country that performs or promotes abortion services – often referred to as the "Mexico City policy." Long a Democratic priority to remove the policy, President Clinton had repealed it during his administration, only to see it reinstated by President Bush in 2001 through an executive order. The amendment, by Sen. Barbara Boxer, D-Calif., was offered to the bill that funds U.S. foreign operations, such as peacekeeping initiatives and HIV/AIDS prevention programs.

Boxer argued that this policy hamstrings women's rights and public health groups in foreign countries that try to provide family planning choices, or that lobby foreign governments over inadequate health policies. Boxer said many of these organizations find themselves "gagged" when it comes to speaking out about issues of health and women's rights, because they are afraid to lose U.S. funds for their other initiatives.

"Colleagues, I wish to tell you a story, a compelling story of what happened in Nepal in 2001. A little 13-year-old girl was raped in Nepal by her uncle. A family member took her for an abortion. Under the laws of Nepal, they sentenced that little girl to 20 long years in jail. Because a family planning agency helped her and because that family planning agency in Nepal, an NGO, spoke out on behalf of changing the laws that put a little girl in jail and let the uncle free, America withheld its funds. That is shameful. It is wrong. Please help me overturn this Mexico City global gag rule."

Many progressive also chafe at the idea that a moral objection to abortion services or information about family planning should be enshrined in U.S. law, particularly in poor countries where information about sex education and contraceptives are minimal.

Conservatives, on the other hand, believe that rescinding the policy would lead to U.S. funds being used to perform abortions in foreign countries, and that as a result the number of abortions would spike. "We won't support groups that fund abortions overseas. You can be pro-choice and say: I think that makes sense, because I don't think we should use taxpayer funding to support abortion or to promote abortion policies overseas. We should let them decide this deeply moral subject that is a very difficult subject in our country, let alone in places around the world," Brownback said.

Sen. Patrick Leahy, D-Vt., said the conservative argument that taxpayer money could be used to fund abortions if this policy were lifted is a straw man. "Our law explicitly prohibits any U.S. funds from being used for abortion or to promote abortion," Leahy said. But he added that the Mexico City policy goes further because it prohibits federal money from supporting private family planning organizations that provide information or advice about abortions, or to advocate for safe abortion practices. "If we tried to impose the Mexico City policy on any family planning organization within our borders, it would violate the first amendment. But we impose it on those same organizations when they work overseas beyond the reach of our Constitution," Leahy said.

Some Republicans also have expressed reservations because the White House has threatened to veto any piece of legislation that contains a provision lifting the policy, as well as a blanket veto threat against any measure that weakens current pro-life policies.

"There's no point in getting the bill vetoed on this issue," said Sen. Judd Gregg, R-N.H.. "I'm a little surprised that the Democratic majority has decided to reopen it."

The amendment was adopted 53-41 on a close, mostly party line vote, with just a handful of defectors. Seven Republicans voted yes, of whom three are women – Olympia Snowe of Maine, Susan Collins of Maine, and Lisa Murkowski of Alaska. One Democrat voted no – Ben Nelson of Nebraska, who opposes abortion in most instances. He was also the only Democratic senator who voted against expanding stem cell research in 2006.