The Sunnis' dilemma: accept a secondary role in a government led by Shiite Prime Minister Nouri al-Maliki or see their community completely marginalised - which could increase support for the insurgency.
Agreeing to the deal behind closed doors on Wednesday, then dramatically walking out of parliament in protest a day later, the Sunni-backed Iraqiya coalition left itself without a clear next step.
The coalition had demanded the right to form the government after its first-place finish in the 7 March parliamentary election. Iraqiya won 91 seats compared to 89 for al-Maliki's coalition - nowhere near a majority, but still bragging rights for minority Sunnis who dominated the country during Saddam Hussein's regime.
Iraqiya is led by former prime minister Ayad Allawi, a secular Shiite with strong support from Sunnis, who knew that one of their own Muslim sect wouldn't have a shot at the prime minister's job. After months of negotiations, it was Mr al-Maliki who was able to win support from enough other blocs for a majority coalition. On Thursday, newly re-elected president Jalal Talabani, a Kurd, asked Mr al-Maliki to form the next government.
Many Sunnis said they felt robbed. "We were hoping for a change in the political map in Iraq," said Sheik Ahmed Muhsen al-Sahi, a tribal leader from Anbar province west of Baghdad.
Under a deal worked out this week, Iraqiya was to get the parliament speaker's post and Mr Allawi was to chair a new council with authority over issues such as security and foreign policy. But the two sides quickly began to disagree over what powers this council would have. Iraqiya also accused al-Maliki's Shiite allies of betraying an agreement to overturn a ban on three lawmakers who were barred from parliament seats for alleged ties to Saddam Hussein's Baathist party.
Sunnis view so-called de-Baathification as a flagrant attempt to keep them from power, but the flare-up also demonstrated a larger problem. After years of sectarian warfare in Iraq's streets, Sunni and Shiite political leaders simply don't trust each other.
The walkout from parliament also underscored how few options are open to Iraqiya. The session went on without them. Talabani was re-elected and asked al-Maliki to form the next government. Members of al-Maliki's coalition said the government would move on with or without Iraqiya, indicating little willingness to compromise. And about 15 Iraqiya members also chose to stay in the session.
An Iraqiya spokeswoman denied any split, but it was evident the coalition had problems.A group of Iraqiya lawmakers earlier in the week said they would support al-Maliki regardless of what the rest of the coalition did. Khadum al-Shimmari was one of them, and he remained in the parliament session on Thursday.
"We had hoped the first parliament session would start without problems and fiery statements. We were looking for a good start, full of good intentions, but the contrary took place," he said.
Sunnis have long had a problem achieving unity in post-Saddam Iraq. The Shiites too have been fractured but they form the dominant majority and will play an important role regardless of their divisions. In fact, it was only because the Shiite parties split before the election and the Sunnis rallied behind one bloc that Iraqiya was able to win a plurality.
America has pushed heavily for an Iraqiya role in the next government. The risk of leaving them out entirely is that Sunnis disillusioned with the political process may yet again support the insurgency, a dangerous prospect at a time when US troops are going home.