Buenos Aires and Kigali are essentially a lock to take their places on the 15-member council, as no other countries in their respective regions have declared any intention to vie for a spot on the most powerful UN body.
There is, however, competition in Asia -- with South Korea leading the charge -- and the so-called Western European and Others Group, in which Australia and Finland are the frontrunners over Luxembourg.
For the Asia-Pacific seat, South Korea has the clear advantage over Bhutan and Cambodia. Seoul has highlighted its participation in 19 peacekeeping operations since it joined the world body in 1991.
Cambodia in contrast has not led an active campaign, diplomats said, while Bhutan has no formal diplomatic ties with any of the council's five permanent members -- Britain, China, France, Russia and the United States.
"It is not a very good starting point" for the remote Himalayan nation, one diplomat said.
In the other group, Australia and Finland are seen as having the edge over Luxembourg, a founding member of the European Union.
Australia -- which has already sat on the council four times -- has lobbied intensely for the place. Finland has had two terms. Luxembourg, Bhutan and Cambodia have never been on the council.
Nations must garner 129 votes, or two-thirds of the 193-nation General Assembly, to be elected. Surprises are rare but can happen -- in 2010, Canada was shocked when it lost out to Portugal and Germany.
The five countries chosen will on January 1 begin a two-year term. They will replace Colombia, Germany, India, Portugal and South Africa.
The five other non-permanent members are Azerbaijan, Guatemala, Morocco, Pakistan and Togo. Their terms will be completed at the end of 2013.
Only the five permanent members have veto-wielding power.
Last year, Pakistan's election raised fears of a conflict on the council with its longtime rival India, but the two South Asian states served together without difficulty -- and voted together often on issues such as Syria.
This time, Argentina would serve alongside Britain, but their longstanding dispute over the Falkland Islands is not expected to be a factor in the council's deliberations.
If predictions are accurate, according to one diplomat, the emerging BRICS nations -- Brazil, Russia, India, China and South Africa -- will lose influence on the council, with India and South Africa leaving.
Even though the permanent five will maintain their predominant influence, each new member will bring with it its allies and issues of concern.
Rwanda, accused of interference in the Democratic Republic of Congo, has the support of the United States, and South Korea should play an active role in debates on North Korea.
Argentina has a particular interest in Haiti, where it has sent hundreds of peacekeepers.