Iyad Allawi went into exile in the 1970s after falling foul of Saddam Hussein
Iyad Allawi was denounced by many Iraqis as an American puppet when he stepped down as prime minister five years ago.
But the British-trained neurosurgeon has again become a leading contender for the job after his Iraqiya bloc's narrow victory in March's parliamentary election.
Barring a successful challenge by Prime Minister Nouri Maliki's State of Law alliance, Mr Allawi will be given the opportunity to form a coalition government, paving the way for weeks of political wrangling.
A secular Shia, he has promised that Iraqiya "will open its heart to all political forces and all those who want to build Iraq".
Mr Allawi is well-connected in Washington and London, has extensive business interests, and has close relations with Saudi Arabia.
Born in 1945 to a prominent Shia Muslim merchant family, Mr Allawi joined the now banned Arab nationalist Baath Party as a young man.
Born 1945 to leading Shia family
Trained in UK as a neurologist
Former Baathist; exiled after falling out with Saddam Hussein
Survived an assassination attempt in 1978 while living in London
Co-founded Iraqi National Accord in 1991 after invasion of Kuwait
Backed failed 1996 attempt by Iraq army officers to oust Saddam
Became member of post-invasion Iraqi Governing Council in 2003
Appointed prime minister of Iraq's transitional government in 2004
Iraqi National List third in 2005 parliamentary election
Iraqiya alliance wins 91 seats in 2010 parliamentary election
But he fell out with Saddam Hussein in the early 1970s after the party came to power and was forced to go into exile in the UK, where he completed his medical training.
He was badly wounded in an assassination attempt while living in Kingston-upon-Thames in 1978, believed to have been ordered by Saddam.
The assailant attacked Mr Allawi in his bedroom with an axe, nearly severing his right leg and inflicting a deep wound in his chest.
Mr Allawi spent a year in hospital recovering from his injuries, after which he began to organise a network of opposition to Iraq's future president.
In the 1980s he travelled extensively in the Middle East, holding meetings with other exiles, and cultivating links with rebel army officers still in Iraq.
After Iraq's invasion of Kuwait in 1990, Mr Allawi co-founded the Iraqi National Accord (INA), which became known for attracting disillusioned former Baathists, and for its close links with Western intelligence agencies.
With the backing of MI6 and the CIA, the group supported the idea of fostering a coup from within the Iraqi army to overthrow Saddam. But its attempts ended disastrously, most notably in 1996.
The defection to Jordan the previous year of the Saddam's son-in-law, Hussein Kamil al-Majid, encouraged the INA and the CIA to believe that the president was losing his grip on power.
But the coup was foiled when Iraqi intelligence agents penetrated the INA's dissident operations inside Iraq. In June 1996, 30 military officers linked to the INA were executed and another 100 arrested.
'Saddam without a moustache'
In the aftermath of the invasion in 2003, Mr Allawi returned to Iraq and
became a member of the US-appointed Iraqi Governing Council
During that time, he focused on running the IGC's security committee, which was responsible for reforming the army, police and intelligence services. He opposed the purging of members of Baath party from government positions.
Mr Allawi's Iraqiya bloc received votes from disaffected Sunnis and Shias
In June 2004, Mr Allawi was
provisionally appointed Iraqi prime minister
by Washington and led a transitional government for just under a year.
His tenure was marked by allegations of widespread corruption, collaboration with the US, and a hardline stance on security - the last attribute led some Iraqis to nickname him "Saddam without a moustache".
Mr Allawi supported the controversial US offensives to regain control of the predominantly Sunni Arab city of Fallujah in 2004, and against the Mahdi Army of the radical Shia cleric Moqtada al-Sadr in Najaf.
He also did little to dispel a rumour that he personally shot dead several suspected insurgents at a police station in Baghdad in 2004.
Mr Allawi's government could do little, however, to prevent Iraq sliding into sectarian conflict, and his secular Iraqi National List alliance fared poorly in the parliamentary election of 2005, coming a distant third to the Shia-led United Iraqi Alliance.
Despite winning election to the newly formed Council of Representatives in the second poll that year, he spent most of the subsequent years out of Iraq.
Then in 2009, Mr Allawi launched al-Iraqiya (Iraqi National Movement), a nationalist alliance which includes Iraqi Vice-President Tariq al-Hashemi, a Sunni Arab, and Sunni politician Saleh al-Mutlaq.
While all of the major coalitions spoke of "national unity" ahead of the 7 March election, Iraqiya had a more consistent anti-sectarian perspective than most of their rivals and received many votes from disaffected Sunnis and Shias across Iraq.