CHRONOLOGY: Political events since Iran's revolution

(Reuters) - Iranian politicians have begun campaigning ahead of a parliamentary election on Friday that may offer pointers to President Mahmoud Ahmadinejad's popularity.

But voters will be able to choose only among candidates who survived a vetting process that eliminated two-fifths of those who applied, including many leading reformists.

The three main lists comprise conservatives including Ahmadinejad allies, conservatives who broadly oppose the president, and reformists who are his most vocal critics.

The poll will be seen partly as a verdict on Ahmadinejad, who has pursued assertive foreign and nuclear policies while spending Iran's windfall oil earnings freely. But his prospects for re-election next year may depend more on whether he can retain the support of Supreme Leader Ali Khamenei.

Here is a chronology of the main political events since the 1979 revolution and the founding of the Islamic Republic.

January 1979 - Shah Mohammad Reza Pahlavi is forced into exile after mounting discontent with his authoritarian rule.

February - Ayatollah Ruhollah Khomeini returns to Tehran from Paris after 15 years of exile spent mainly in Iraq and quickly consolidates his power to become Supreme Leader.

June 1989 - Khomeini dies. Ayatollah Ali Khamenei appointed Supreme Leader.

August 1989 - Pragmatic dealmaker Akbar Hashemi Rafsanjani becomes president after landslide election win.

May 1997 - Reformist Mohammad Khatami is elected president in landslide over candidate backed by conservative clerics.

July 1999 - Student unrest turns violent over closure of pro-reform newspaper. Dozens of such newspapers are later shut.

February 2000 - Khatami's pro-reform allies sweep to big win in parliamentary election against entrenched conservatives.

June 2001 - Khatami is re-elected president.

August 2002 - Exiled opposition National Council of Resistance of Iran reports existence of uranium enrichment facility at Natanz and heavy water plant at Arak.

February 2004 - Conservatives win parliamentary polls after Guardian Council bars some 2,500 reformers from standing.

June 2005 - In major upset, Mahmoud Ahmadinejad, mayor of Tehran, defeats Rafsanjani in run-off vote for presidency.