FACTBOX: Facts about Zimbabwe's Tsvangirai

(Reuters) - Zimbabwean opposition leader Morgan Tsvangirai was preparing to announce he was pulling out of a run-off presidential election, a source in his party said on Sunday, after President Robert Mugabe's supporters attacked his rally.

Below are some facts about Tsvangirai:

* Tsvangirai is a former union leader who has been a thorn in Mugabe's side for a decade as the head of the Movement for Democratic Change (MDC), the main opposition group.

* The son of a bricklayer, Tsvangirai was born in 1952 in central Zimbabwe.

* He worked in a mine to feed his family and cut his political teeth in the labor movement as a mine foreman.

* Tsvangirai helped found the MDC in 1999. Despite intimidation, it stunned the ruling party by winning 57 of 120 seats in a 2000 parliamentary vote.

* Tsvangirai was acquitted of plotting to assassinate Mugabe and seize power before a 2002 presidential election.

* Mugabe's party won a crushing majority in a 2005 parliamentary election, which the MDC said was rigged.

* The MDC split in 2005 in a feud over how to tackle Mugabe. A splinter group accused Tsvangirai of behaving in a dictatorial fashion.

* Tsvangirai was arrested at an anti-Mugabe rally in 2007. He said he had been attacked at a police station. Critics said the incident helped revive his sagging political fortunes.

* The second round follows the disputed 2008 presidential election in which official results showed Tsvangirai beat Mugabe, but not by enough votes to avoid a run-off.

(For full Reuters Africa coverage and to have your say on the top issues, visit: africa.reuters.com/ )

(Writing by David Cutler, London Editorial Reference Unit)