As part of the State Department funding bill, the Senate could consider whether to make permanent Obama's repeal of the controversial so-called Mexico City policy.

When in effect, the policy prevents foreign nongovernmental organizations that provide or counsel women on abortion from receiving U.S. aid.

If approved, the provision would write into law a prohibition on withholding foreign assistance to groups that provide such services, as long as they are legal in the receiving country and the United States.

Sen. Frank R. Lautenberg, D-N.J., who sponsored the proposal as an amendment to the State Department funding bill, says it would end the uncertainty that foreign aid recipients face when control of the White House shifts between parties.

Whenever legislation includes abortion language a vigorous debate is guaranteed. Even in the Senate, where the proportion of members that support abortion rights is higher than in the House, the Lautenberg provision is sure to cause trouble for the foreign operations bill.

The committee that drafted the House version of that appropriations bill took pains to avoid such controversy by including a line in the legislation clarifying that it would not change any laws restricting funding for overseas abortions.

The Senate leadership may try to convince Lautenberg and other supporters to drop the provision to avoid holding up the rest of the State Department's funding.

Anti-abortion groups warn that debating a permanent end to Mexico City could take weeks, time the Senate can't afford to spare with health care overhaul, climate change and annual appropriations bills on the horizon.

Here's the rundown:

THE MEXICO CITY POLICY

A federal policy put in effect by Republican presidential administrations from 1984 to 1993 and 2001 to January 2009 which prevents U.S. aid from going to foreign groups that provide or promote abortion.

HISTORY:

Named after the city where it was announced by President Ronald Reagan in 1984, the Mexico City policy has been intermittently imposed or repealed by successive presidential administrations.

President Bill Clinton overturned the restriction when he took office in 1993, President George W. Bush reinstated the policy in 2001 and Obama again overturned it during his first week in office.

The 1973 so-called Helms amendment, which is still in effect, prohibits U.S. funding from paying for overseas abortions. The Lautenberg amendment would not affect that prohibition.

KEY SUPPORTERS:

Sen. Frank R. Lautenberg, D- N.J.

Rep. Nita Lowey, D-N.Y.

Members of the Congressional Pro-Choice Caucus

Center for Reproductive Rights

National Abortion Rights Action League

Population Action International

ARGUMENTS IN FAVOR:

* A permanent repeal is needed to avoid "flip-flopping" on the issue of funding for foreign groups that council or provide abortions. Recipients of foreign aid are confused and may avoid taking funding from the U.S. because of the uncertainty created when different presidential administrations overturn or reinstate the restriction.

* The policy can actually lead to more abortions by cutting off foreign groups that provide contraception and counseling from U.S. funds, resulting in more unintended pregnancies.

* The Mexico City Policy violates free speech and the disclosure of accurate medical information.

KEY OPPONENTS:

Rep.  Kay Granger, R- Texas

Sen. Sam Brownback, R-Kan.

Members of the Congressional Pro-Life Caucus

National Right to Life Committee

United States Conference of Catholic Bishops

ARGUMENTS AGAINST:

*A permanent repeal would constrain the president's authority to place conditions on foreign aid.

* Without the policy, groups acting in countries where abortion is illegal can use U.S. funds to circumvent domestic law.

* With abortion such a contentious issue in the United States, tax-payer funds should not be used to aid foreign groups that counsel on or lobby for abortions.

KEY VOTES

On the final vote of the Senate Appropriations Committee on the State Department funding bill that contains the Lautenberg amendment, Brownback was the lone sole "no," a vote he says he cast in protest of the Mexico City language.

Sen. Mary L. Landrieu, D-La., and George V. Voinovich, R-Ohio abstained from the vote saying they wanted to avoid abortion controversy that could derail the bill.

The Senate could take up the State Department bill and the Lautenberg provision in the coming weeks.

Caitlin Webber writes for Congressional Quarterly.