One success the government did have was to convince some of the Sunni Arab tribes out there to join the government, and get some reconstruction goodies in return. But all this did was send the extremists in those tribes off to join al Qaeda. These reinforcements have helped keep al Qaeda viable, because the terrorist organization has made itself very unwelcome in most of Iraq, including many Sunni Arab areas.
The Baath Party (pro-Saddam) Sunni Arab nationalists still have thousands of fighters in play, backed by cash and fear of prosecution for terrorist acts (going back to Saddam's days). Add to that hundreds of al Qaeda, and thousands of diehard Sunni Arab tribesmen in Anbar, plus a population that will not accept foreigners (including Kurds and Shia Arab Iraqis) with guns among them, and you have the wild, wild west. May not stay that way for long, though. Despite the losses, the government is willing to keep sending troops and special police battalions to Anbar. Month by month, there are more Iraqi security forces able to handle Anbar. Meanwhile, the tribes are not getting any stronger. Do the math. And remember that there's a growing attitude among the majority of Iraqis (Kurds and Shia), that the country would be better off with no Sunni Arabs at all. This is never even brought up by the government, but it commonly heard on the street, where the police and soldiers are recruited from.
Anbar province in Iraq is truly becoming the "wild west." This large, mostly desert, region of western Iraq has long been dominated by over a dozen Sunni Arab tribes. Even Saddam Hussein handled these tribes gently, and made them allies after the 1991 Shia rebellion. The people of Anbar are among the poorest, and least educated, of the Sunni Arabs who have long dominated what is now Iraq. The much wealthier and well educated Sunni Arabs of Baghdad looked on the folks out west as a bunch of desert bumpkins. But with the Kurds and Shia now dominating the government, there's a lot more Sunni Arab solidarity. For that reason, the government, and coalition troops, largely stayed out of Anbar until about a year ago. Since then, there has been lots of fighting in Anbar. The terrorists, and Sunni Arab nationalists, have not been able to keep American troops out, but they have been able to terrorize most Iraqi soldiers or police who try to control the region. So there is now a situation where we're not winning, we're not losing; it's basically a stalemate.