The Palestinian leadership has now made clear that they will seek full UN membership through the Security Council (rather than opting for something less by going directly to to the General Assembly).
The ultimate outcome here is not in doubt: if necessary, the United States will use its veto. But it may not come to a veto. If the Palestinians cannot muster nine votes, the 15-member Council cannot act. It's very possible that their supporters will at that point choose not to introduce a formal resolution. From a political perspective, the distinction between a resolution that fails to gain nine votes and one vetoed by the United States is significant, and the United States undoubtedly will be pulling out the diplomatic stops to see that the Palestinians do not muster the magic nine votes.
Here's my current assessment of where the current Council members stand (note: I'm updating this assessment regularly as new information becomes available):
Bosnia and Hercegovina:
Very likely to Might support Palestinian membership. Arab ambassadors to Bosnia have reportedly been lobbying Bosnian leaders, reminding them of their support to Bosnia's Muslims during the 1992-1995 conflict. Update: An informed reader says Bosnia's position is more complicated than I allowed initially:
Bosnian Serb leaders strongly oppose the Palestinian initiative due to ties with Israel and, especially, belief that this action could lead to a similar move by Kosovo. Both Bosnian Serbs and Serbia regard Kosovo as having wrongly declared a "unilateral" independence from Serbia and are thus likely to be against any remotely analogous action. (This is more about Balkan-specific issues than about Orthodoxy vs. Islam).
In addition, BiH has tended to follow EU positions when voting on the UNSC and to take US views very much into account, as seen in voting on Libya earlier this year. Absent an EU consensus and given apparent US opposition, abstention seems more likely than a "yes" vote.
I'm convinced that Bosnia's situation is uncertain and that abstention is a real possibility. I've adjusted the count below accordingly.
Brazil: Likely to support membership. Brazil surprised Washington late last year by recognizing Palestine.
China: Likely to support membership. Beijing has recently indicated its support for the Palestinian membership bid.
Colombia: Likely to oppose membership. Israel has had good relations with Colombia recently and has lobbied the Colombian government to oppose the Palestinian bid.
France: On the fence, although these comments from foreign minister Alain Juppe do not sound very favorable to the membership bid.
Gabon: On the fence. More: France should have a significant impact on Gabon's position (for recent allegations of financial entanglements between French politicans and Gabon, see here). This Ha'aretz report suggests that Gabon will support the Palestinian bid.
Germany: Unlikely to support. Often supportive of Israel, Germany's foreign minister recently signaled his displeasure at the Palestinian membership campaign.
India: Very likely to support membership.
Lebanon: Almost certain to support membership.
Nigeria: Likely to support membership.
Portugal: On the fence, but Ha'aretz reports that Lisbon is leaning toward supporting the bid.
Russia: Likely to support membership.
South Africa: Likely to support membership
United Kingdom: On the fence. British leaders appear to still be undecided.
United States: will not support membership.
eight seven members who are likely to support, two leaning in that direction, four three who are probably on the fence, two likely to oppose, and one certain to oppose. As one Security Council diplomat told me last week, this is shaping up to be a very close call. There are several quite important considerations. First, Council members need not take a position; abstention is an option, and one that will work against the Palestinians and their supporters, who need affirmative votes to force a U.S. veto. Second, the European Union (which accounts for four votes) may be in a decisive position if it adopts a common position. Finally, it is well documented that foreign aid has been deployed in the past to sway Council votes. I wouldn't be at all surprised if someone in the State Department were hurriedly checking on Gabon's aid package to see what leverage might exist.
More: For an interesting argument that the Palestinian decision to approach the Security Council may actually defuse a dramatic showdown, see here. The basic point is that the Council can sit on the issue while the rest of the General Assembly meetings proceed.
Even more: Some readers are skeptical that it matters much whether a membership resolution fails in the Council by lack of nine votes or by U.S. veto. I understand the skepticism but I do think the cause of death matters at the level of public perception. And, ultimately, that's what the whole membership drive is about.