He was a presidential patron, then a pariah; an alleged fraud, then an economic saviour. And, perhaps more remarkably, he was groomed by Washington, lured by Iran, and is now being courted by both as a man who could rescue Iraq.

The mercurial career of Ahmad Chalabi has been central to much of the turmoil that Iraq has gone through in the past 20 years. From guerrilla leader in exile in the Kurdish north to the pinup boy of the Pentagon's war plans, Chalabi was more responsible than any other Iraqi for the ousting of Saddam Hussein more than a decade ago.

His Iraqi National Congress (INC) fed much of the false information about Saddam Hussein's links to al-Qaida and non-existent weapons of mass destruction. And for many years before that, Washington had funded the group's subversive efforts.

Chalabi's numerous foes say he has been just as instrumental in the years of chaos that have followed, turning within a year of the US invasion towards Iran, with whom he has since forged deep ties at the expense of the government that brought him there. Along the way, he has led a purge of former Ba'athists, alienated Iraq's Sunnis, manoeuvred incessantly in the byzantine corridors of Iraqi politics, and yet somehow emerged as a figure who could steward the country through its greatest test.

Throughout the past month, Chalabi's name has consistently been touted as a potential prime minister to replace the besieged incumbent, Nouri al-Maliki. With every town and border post that fell to the Isis jihadists, and as Kirkuk and the disputed territories were effectively annexed by the Kurds, Maliki's position has become ever more untenable. Chalabi, meanwhile, has been mooted as one of the few who could stop Iraq's slide towards disintegration.

Iraq has very much had a "back to the future" feel since the jihadists rode into town: political torpor, ethnic tension and – albeit a decade older – familiar faces. Solutions remain elusive, though. "None of us like the guy," said a senior cabinet minister, who – like many others – asked not to be identified. "But I realise, and so do my friends, that he has more capacity than all of us."

Ammar al-Hakim, the leader of the Supreme Islamic Council, on whose ticket Chalabi ran in a national election held on 30 April, conceded that the 69-year-old was one of his lead candidates for prime minister should Maliki be forced out. "We need men like him," he said. "The country cannot afford to let good people go to waste."

The hardline Shia Sadrist movement is backing Chalabi too, as are the Kurds with whom he has forged abiding ties over the past two years. By convention in post-Saddam Iraq, Shias take the prime minister's chair, Sunnis claim parliamentary speaker, and the Kurds take the presidency.

The trouble for the staunchly Shia, though liberal, Chalabi is the political arithmetic. Together, Hakim and the Sadrists can only muster 63 seats, far fewer than Maliki's State of Law list, which won 92 seats. State of Law, and in particular the Dawa party from which Maliki hails, are demanding that whoever leads the country must come from their ranks. Most see Chalabi as an imposter.

"I saw the prime minister yesterday and the subject of Chalabi came up," said one senior MP. "Maliki responded: 'Don't talk to me about the guy in the red underpants'." Chalabi swims most days, in red swimming trunks.

Though the numbers seem to be against him, Chalabi has renewed traction among regional and global stakeholders. Even the US is paying attention. In what has been perceived as a nod to the scale of the crisis facing Iraq, the US ambassador to Baghdad met Chalabi in the middle of June. The gathering is thought to have been the first discussion between a senior State Department official and the man they once championed since a bitter falling-out between both sides in June 2004.

At the time, the US alleged that Chalabi's security chief, Aris Habib, had told Iran that the US had cracked an Iranian communications code. They alleged that Chalabi had gleaned the information from a drunken US official. When told of the news, George W Bush told Pentagon officials: "I want Chalabi off the payroll." Within days, the $330,000 per month paid by the Defence Intelligence Agency to Chalabi's Iraq National Congress was cancelled. The snub severed co-operation going back at least a decade, costing the US government at least $33m, most of which was paid directly to the INC. Only months before turning on him, Laura Bush had hosted Chalabi while her husband delivered the 2004 State of the Union address.

Chalabi rolls easily with his fluctuating fortunes, knowing that a powerful patron is never far away. His interests have since spanned the full arc of Iran's regional causes. In the early days of the uprising in Syria, he was a regular visitor to the Assad regime's security overlord, Mohamed Nassif. He also advised the the Wefaq opposition party in Bahrain as the Shia insurrection against the Sunni minority monarchy raged.

His main backing, though has come from the Iranian general Qassem Suleimani, the head of the Quds Force of the Revolutionary Guards, who acts as puppet master in Baghdad, as well as Damascus and southern Lebanon. Through Suleimani, Chalabi has power and influence that far outweigh his political fortunes. Suleimani visited Baghdad within days of Chalabi's detente with the US embassy.

The son of an establishment Baghdad family, Chalabi left Iraq as a child in 1956, spending much of his time between the US and the UK, along with stints in academia in Lebanon and finance in Jordan from the early 1970s. Along the way, he received a doctorate in mathematics and founded Petra Bank in Amman, which failed more than a decade later.

"In all of Iraq, nobody knows how to punch above their weight or play the convoluted game of Iraqi politics better than Ahmad Chalabi," said Ramzy Mardini, a Jordan-based political analyst for thinktank The Atlantic Council. "His enduring survival is beyond our comprehension. Unlike Ayad Allawi [another former exile], Ahmad Chalabi is close to Iran. This is the key relationship that makes Chalabi's candidacy something of a realistic prospect should Maliki be ousted. If Iran has a redline against a candidate, [he doesn't] have a shot in making it in the end.

"If Iraqi politics were Game of Thrones, Chalabi would play Lord Baelish, a consummate puppet master behind the scenes, constantly plotting his path to power. For him, chaos isn't a pit, but a ladder and Chalabi knows the ways and means of exploiting a crisis to suit his interests and elevation in Iraq's political circles. He apparently has good relations with everyone, except Maliki."

The next month will determine how willing Chalabi's patrons are to throw in their lot with him. Maliki, apparently emboldened after a private talk with the office of Iraq Shia Islam's highest authority, Ayatollah Ali al-Sistani, said on Friday that he was not going anywhere. Some of those touting Chalabi as leader are now saying he would be a better fit for finance minister.

"His lesson is that you are never finished here if you know how to manoeuvre," said the cabinet minister. "He can't be written off."