He came to power by (mostly) the support of Al-Sadr, a prominent Shiite cleric who is the head of the militia group; The Mehdi Army (estimated to be +60,000 strong).
With the country coming in a brink of civil war in late 2006 (after the bombing of the shrine of Samara) to early 2007 all seemed hopeless, but nope. When President Bush announced the "surge" in January 2007(?) violence has (currently) reached a 4 year low and political progress has been made that would have never have happened if it weren't for the "surge"(IMO). Politically, the parliament has passed an amnesty law: mainly for Sunni captives, giving pensions to ex government officials from the Saddam era, goal reached for having substantial number of security forces, ect.
Once a "liberal" city during the Saddam era, Basra during the most of the war was met with strong religious Shiite militias because of the incompetence of the Britsh
In March of 2008, Maliki gained support of Sunnis for cracking down on Shiite militia in Basra; mostly the Mehdi Army (I find this impressive because Al-Sadr pretty much gave the job to Maliki back in 2006). The crackdown has also been praised by the Kurds and Shiites not loyal to Sadr. This shows that Maliki does not have sectarian bias or at least a very little one.
After the crackdown in Basra, Maliki had his sites on Sadr City; the main urban sanctuary of the Mehdi Army. The fighting was bloody for about a month and after that a cease fire was made by Sadr (probably not to look like even more of a cunt). Once the cease fire was made IRAQI security forces entered the stronghold to set up military check points. Since the presence of Iraqi troops Sadr City has been relatively calm.
To rid Al Qaeda in Iraq Al Maliki ordered forces to be sent to Mosul (dubbed AQI's last urban strong hold). Thousands of suspected fighters have been captured and according to a general commanding American forces in northern Iraq the province has seen a 80% decline in violence from a year ago (!).
And there you go boys and girls....