FACTBOX: Iranians vote in parliamentary election

(Reuters) - Iranians voted on Friday in a parliamentary election that conservatives are expected to win after many pro-reform politicians who oppose hardline President Mahmoud Ahmadinejad were barred from the race.

But Ahmadinejad is not guaranteed an easy ride even with a win by conservatives because the camp includes allies of the president, critics of his economic policies, and those looking beyond this election to the presidential race next year.

Following are some facts about Iran's eighth parliamentary election since the 1979 Islamic revolution:

* QUALIFICATION OF CANDIDATES:

-- Candidates for the 290-seat assembly were screened by government-run committees and the Guardian Council, a conservative body of clerics and jurists that checks hopefuls for commitment to Islam and other criteria.

-- After the vetting process, some 4,500 candidates have been left to run from about 7,600 who originally signed up.

-- Reformists see disqualifications as an attempt by hardliners to keep them out of power. The Council denies bias.

* CAMPAIGNING

-- Iran has no tradition of disciplined party membership or detailed party platforms. Three main groups -- two conservative and one pro-reform -- have emerged. But some candidates are backed by more than one group and allegiances often shift.

They are:

-- UNITED FRONT: The biggest conservative group, which includes supporters and critics of Ahmadinejad. It is the most pro-government group and is expected to win most seats. Conservatives label themselves "principlist" for their loyalty to the ideals of the Islamic Republic.

-- INCLUSIVE COALITION: This conservative group is backed by Ahmadinejad rivals such as Ali Larijani, who quit as nuclear negotiator last year citing differences with the president, and Tehran mayor Mohammed Baqer Qalibaf. Both lost to Ahmadinejad in the 2005 presidential race and may still eye the presidency.

-- COALITION OF REFORMIST GROUPS: The figurehead for this group is former President Mohammad Khatami. Reformists lost control of parliament in 2004 and hopes of a comeback have been dashed by the vetting process, so they can contest no more than half the seats. Reformists back social and political change but, except for a radical wing, back the Islamic Republic's ideals.

-- Such coalitions may play a bigger role in cities but in smaller towns and provincial areas much will depend on the reputation of candidates and personal contact with voters.

* THE VOTE AND THE RESULT

-- There are about 44 million eligible voters, who must be over 18 years, in the country of 70 million people.