The general line of attack is that had Bush not invaded Iraq, or had done so differently, then the Child Emperor, the Lightworker, would not be flopping about like a carp on the beach.
For instance, the rather credulous Michael Tomasky writes in Obama drafted to fight Bush's war:
So let me run this depressing thought by you: They have every chance of ending with Barack Obama, and undoubtedly his successor as well, having to prosecute the war that George W. Bush and his geniuses made inevitable with their lies and errors and perversions of law and criminally irresponsible fantasies about this Iraq that they promised us would reveal itself before our eyes as painlessly and quickly and even beautifully as a rose coming to bloom in time-lapse photography.
In short, this is the mark of the stunted intellects that have been attracted to Obama from the beginning. Much of his critique has already been addressed here but rather than let this current calumny go unanswered let's go through it again.
Let's stipulate that every thing Tomasky says is the unalloyed truth. Personally, I think it is as dishonest a critique as anyone is likely to find outside a Tom Ricks article or Democratic Underground, but arguendo let's accept it. His critique only takes us up to around 2007. What happened in the intervening seven years to get us here. How did a situation that was under control and improving in 2007-2008 turn into an absolute dog's breakfast of bad stuff?
Obama had politically locked himself into a firm timeline for withdrawal from Iraq. The idea of letting your enemies know your intentions has long been frowned upon in both war and diplomacy. It would have been relatively easy for President Obama to modify his campaign pledge. But Obama, like most mediocrities, can never admit error. In this particular case, not only were our enemies told when we were leaving but our friends were told they were on their own.
Because Obama had told the Iraqis that we were leaving, no Iraqi politician had the need to spend political capital and take personal risk to stand up for a Status of Forces Agreement. When Maliki offered us the exact same agreement that US forces are operating under in Iraq at this moment, we rebuffed him. In short, Obama wanted out of Iraq and he wanted it to look like the Iraqi's had forced him out.
Once we left, the level of training and proficiency in the Iraqj military began to deteriorate. More importantly, the intelligence networks we had built from 2003 through 2011 were abandoned.
Though Obama his hailing as a success the replacement of Maliki as prime minister, Maliki was supported by Obama in 2010 after his party had been defeated in the parliamentary elections. Obama is claiming as a victory turning out of office the man he intervened to put in office in the first place.
The history since the Arab Spring has been well trod. Overthrowing Gaddafi gave Islamic radicals a base of operations. Attempting to overthrow Assad destabilized that regime to the benefit of extremists. The flow of weapons into Syria from Qatar and Saudi Arabia found their way primarily to the most extreme movements. By all accounts the forces we backed did little in the way of combat and were closely aligned with the extremists in the field.
Once the potential threat of ISIS/ISIL became obvious, Obama did what he does best... hit the golf links. A resolute US air response acting in coordination with the Iraqi Army and the Kurdish Peshmerga would have eliminated the field army of ISIS/ISIL and forced them back underground.
To make the case that this mess is the fault of President Bush requires you to deny everything that has happened in Iraq since before Obama was first inaugurated in 2009.