On December 14, 2008, President George W. Bush and Iraqi Prime Minister Nouri al-Maliki signed the status of forces agreement (SOFA) under which American military forces would leave Iraq by the end of 2011. But at their press conference announcing the SOFA, an Iraqi journalist hurled his shoes at Bush's head, shouting "This is a gift from the Iraqis; this is the farewell kiss, you dog!"
Five and a half years later, it is Bush's man in Baghdad who is under fire from all sides. And to be sure, Nouri Kemal al-Maliki was Bush's man. The entire house of cards that was Dubya's post-facto strategy to pacify post-invasion Iraq--buying an alliance of Sunni tribal leaders to battle Al Qaeda fighters and Baathist insurgents in the west while helping the government beat back Shiite militias in Baghdad and Basra--always hinged on Maliki's support for an inclusive, non-sectarian ruling coalition. As it turned out, Bush's house of cards in Iraq was already starting to tumble by the time the shoes started flying.
Writing in the New Yorker in April, Dexter Filkins recalled Maliki's ascension to the premiership engineered by the Bush administration. In 2006, Bush undermined the incumbent PM, Ibrahim al-Jaafari, who struggling to form a government:

An avuncular, bookish figure, Jaafari had infuriated Bush with his indecisiveness, amiably presiding over the sectarian bloodbath that had followed the recent bombing of a major Shiite shrine.
During the videoconference, Bush asked Khalilzad, "Can you get rid of Jaafari?"
"Yes," Khalilzad replied, "but it will be difficult."
Difficult, but not impossible. "I have a name for you," a CIA officer told U.S. Ambassador to Iraq Zalmay Khalilzad, "Maliki."

But as Filkins explained earlier this month, "Maliki is a militant sectarian to the core, and he had been fighting on behalf of Iraq's long-suppressed Shiite majority for years before the Americans arrived, in 2003." That also explains in part why John McCain and Lindsey Graham urged President Bush in late 2007 to engineer a coup against Maliki.
As you'll recall, the success of the 2007 U.S. surge in Iraq turned on the American cultivation of Sunni tribal leaders in restive Anbar province already underway since the previous year. The arming of 90,000 "Sons of Iraq" and the new alliance with the Sunni sheikhs helped turn the tide against Al Qaeda insurgents in the west. But GOP Senators John McCain, Lindsey Graham, and Saxby Chambliss fretted that the entire Sunni Awakening could be undone if the Shiite Prime Minister al-Maliki didn't move quickly to seek political accommodation with the minority Sunni and Kurdish communities in Iraq. As Graham put it in November 2007:

"What would happen for me if there's no progress on reconciliation after the first of the year, I would be looking at ways to invest our money into groups that can deliver."

Chambliss was even blunter, telling reporters "If we don't see positive results by the end of the year I think you'll probably see a strong message coming out of Congress calling for a change in administration."
But behind closed doors, Robert Draper reported, McCain months earlier had delivered a much harsher message about al-Maliki for President Bush:

It suddenly seemed that the efforts of the surge might be for naught. And so, shortly after returning from Iraq, McCain and Graham visited President Bush at the White House. According to three individuals with knowledge of the July 11 conversation, the pair advised Bush to cut all ties with al-Maliki unless he showed immediate signs of engagement. Such a move on Bush's part would be tantamount to encouraging a coup against Iraq's first democratically elected prime minister, but McCain and Graham saw the situation as a desperate one. We've got a military strategy that's working, they told the president. And it's being undercut by an Iraqi government that's dysfunctional.
Bush was sympathetic. He'd been giving al-Maliki pep talks for more than six months now, with little to show for the effort. But, he told the two senators, "Who's going to replace him?"
We don't have a good answer for that, they replied. But unless al-Maliki changes, we can't get there.

That's why Filkins, who believes the U.S. should have tried harder to maintain a small legacy force in place after 2011, declared Al-Maliki is "probably the dominant" factor in the current disintegration in Iraq:

Time and again, American commanders have told me, they stepped in front of Maliki to stop him from acting brutally and arbitrarily toward Iraq's Sunni minority. Then the Americans left, removing the last restraints on Maliki's sectarian and authoritarian tendencies.
In the two and a half years since the Americans' departure, Maliki has centralized power within his own circle, cut the Sunnis out of political power, and unleashed a wave of arrests and repression. Maliki's march to authoritarian rule has fueled the reemergence of the Sunni insurgency directly. With nowhere else to go, Iraq's Sunnis are turning, once again, to the extremists to protect them.

That was evident in rapid ISIS takeover of Mosul. The much larger Iraqi army units evaporated in the face of hundreds of ISIS fighters. The Washington Post described the reaction of residents:

For many in the mostly Sunni city, the ouster of the hated national security forces was welcome, offering a sign of just how much the Shiite-dominated government in Baghdad has alienated the Sunni population in the eight years since Maliki came to power.

Now, the security crisis posed by ISIS and its allied homegrown Sunni militias is almost certainly beyond the capability of the Iraqi military to reverse. As Filkins warned Monday:

In any case, the real questions are political, and they center on Maliki. Obama suggested that his offer of help would be determined by the progress the Iraqis make in knitting the country back together. The President didn't say it, but he almost certainly wants Maliki to step down, and American diplomats in Baghdad appear to have begun signalling such a desire to other Iraqi leaders.

To put it another way, Barack Obama is not "the man who broke the Middle East." That title belongs to George W. Bush. As the saying goes, if the shoe fits, wear it.