they ignored the request because hes been a douche and because hes asking for a whole crapton of broad powers they are wary of imo.
Tehran and Al Maliki are allies. The Revolutionary Guard are there to assist the Iraqi governing body, not take it over. We (The US) have also already stated we have a stake in what happens there, and while Maliki has been a disaster of a Bush implant, his government is the team the US will back. Expect more weapons, possible airstrikes, etc. ASAP. Already trying to rush the 12 Apaches the Iraqis have coming.
A side problem is these Iraqi wussies who fled gave up all theirUS weapons. One report said a 400,000 piece cache was taken, as well as hundreds of millions of dollars from a central bank. So the US will likely continue aiding the Iraqi government, but will crank up the heat on some real reforms and giving the minority groups a say, as well as ending corruption (yea right) and keeping hold of our taxpayer funded armaments.
But then theres the issue of the Iraqi Kurds who have been trying to annex a city in Iraq they just took over with ease. It has some biggie oil fields. So thats a kick in the junk because they wont be the immediate focus.
The near term end game is its likely that this lightning advance will get stopped by the militias and Revolutionary Guard, possibly aided by our airstrikes (Iran and US fighting side by side, gives me goosebumps in a good way....first our leaders talk for the first time in decades now potentially a partial "alliance". break down them walls lol). But ISIS (or ISIL) has basically redrawn the Middle East, carving out hundreds of miles of Iraq and Syria for its own. And this branch of Al Qaeda got exiled because they were too extreme....super. But anyhow, once they meet any resistance a stalemate is likely to start, and any sustained effort by Iraqi forces and they should be able to push these guys back.
But its a "very fluid" situation. Stay tuned!