FACTBOX - Iraqi parliament to vote on U.S. troops pact

(Reuters) - Iraq's parliament is due to vote on Wednesday on a pact that would allow U.S. forces to remain in the country for three years. Its passage is seen as likely but not assured.

Here are some facts about the vote:

* Ruling Shi'ite and Kurdish blocs, with the support of some independents, should have enough votes to enact the pact with a simple majority of 138 votes in the 275 seat house.

* The government, however, says it wants more than a simple majority. It needs a broad consensus in order to satisfy leading Shi'ite cleric Grand Ayatollah Ali al-Sistani, who has said all Iraq's main communities must agree on the deal. His approval is crucial because of his status and influence.

* The vote is due to be held Wednesday, but Iraqi parliamentary votes are frequently delayed. Parliamentarians break this week for a holiday recess and a delay could prevent a vote from taking place until they return in mid-December.

* There had been some talk about holding a secret ballot, which could enable members of blocs that are publicly opposed to it to break ranks and support it. There was no sign of that actually happening though.

* Lawmakers loyal to Shi'ite cleric Moqtada al Sadr oppose any deal with Americans outright.

* Once passed by the parliament the pact can still be vetoed by President Jalal Talabani or either of his two vice presidents. Vice President Tareq al-Hashemi belongs to a Sunni political group that has insisted on a referendum.

Here is a breakdown of the positions of the major factions in the 275-seat house.