Iraqi President Jalal Talabani arrived in Germany on Thursday for medical treatment for a stroke, leaving behind a potentially messy battle to replace the Kurdish statesman.
The 79-year-old former guerrilla, who was admitted to hospital on Monday night, has mediated among Iraqi Shi'ites, Sunnis and Kurds, and in the growing dispute over oil between Baghdad and the country's autonomous Kurdistan region.
The potential disappearance of his steadying hand fuels concerns of a succession crisis and tensions between Arabs and ethnic Kurds spilling into open clashes.
Sources told Reuters the president was being treated at Berlin's Charite hospital and a black Mercedes with Iraqi diplomatic plates was seen leaving a Charite campus on Thursday.
Publicly Iraqi politicians wished Talabani a quick recovery, but talk was already turning to his potential departure.
"It will be complicated for anybody to replace him," said Shi'ite lawmaker Ali Shlah. "Talabani's absence will open up the situation wide to different claims."
A year after the last American troops left Iraq, violence is down from the days of intercommunal slaughter that erupted soon after the 2003 invasion that toppled Sunni dictator Saddam Hussein. But sectarianism still runs deep in Iraq's politics.
"Talabani's absence from the scene will most likely intensify the political battles," said Ramzy Mardini, an adjunct fellow at the Iraqi Institute for Strategic Studies in Beirut. "The loss of a credible mediator is one thing, but the opportunism felt on one side and the fear held by the other is something that is quite worrisome."
Prime Minister Nuri al-Maliki, a Shi'ite, is already struggling with Sunni, Kurdish and even Shi'ite rivals over the power-sharing agreement meant to balance posts among religious sects and ethnic Kurds.
Talabani has also mediated between Maliki's Arab-led central government and the Kurdish enclave in the north after the two regions' troops faced off in areas where they dispute jurisdiction, a major escalation of a feud over oil and land.
Under the constitution, parliament elects a new president and a vice president takes over in the interim. The power-sharing deal calls for the presidency to go to a Kurd while two vice president posts are shared by a Sunni and a Shi'ite.
But even that temporary step is complicated. Iraq's Sunni vice president, Tareq al-Hashemi, is a fugitive outside of the country after he fled to escape charges he ran death squads.
The other vice president is Khudair al-Khuzaie, who is seen by some as a hardline Shi'ite from Maliki's alliance.
Among Kurds, analysts said former Kurdistan Prime Minister Barham Salih is favoured as a leader with ties across Iraq's sectarian divide. But there could also be a struggle within Iraqi Kurdistan, where Talabani's Patriotic Union of Kurdistan party shares power with the Kurdistan Democratic Party.
Behind the scenes, some senior Sunni political leaders have suggested they may present their own candidate for the presidency in a challenge to the Kurds, who some Arab leaders see as more loyal to Kurdish interests than Baghdad.
Sunni political sources said those names include Sunni Vice Premier Saleh al-Mutlaq and Finance Minister Rafie al-Esawi.
"I support the idea of an Arab candidate to replace Talabani. The Kurds already got advantage from their positions they have in the state," Aliya Nsaif, from the Sunni-backed Iraqiya block.
Talabani earlier this year helped stave off an attempted vote of no confidence against Maliki as Sunni, Kurdish and some Shi'ite opponents sought to scuttle his government. But the Shi'ite premier may still come out on top.
Maliki has warned he may seek a majority government if rivals within the power-sharing agreement do not allow him to govern and he has reached out to Sunni leaders.
Even fierce critics acknowledge the former Arab language teacher has become a consummate political operator, playing rivals against one another and exploiting weaknesses.
"The deteriorating health of Iraqi President Jalal Talabani is creating potential political problems," said Crispin Hawes in a note from Eurasia Group. "But ... Maliki will see the situation as an opportunity to exert leverage on senior Kurdish and Sunni Arab politicians."