Here is a good summary -
http://www.politifact.com/truth-o-meter/statements/2015/may/18/jeb-bush/obama-refused-sign-plan-place-leave-10000-troops-i/
Bush agreed to the withdrawal deadline and agreed not to leave behind a residual force. Obama wanted a small force to remain but could not get Iraq to agree to the terms of our leaving people there.
Full Transcription of Biden's remarks below edited by me to make shorter.
SCARBOROUGH: So what do you say to critics who is say you go back six years, you go to 2010, where there actually was stability in Iraq, by -- certainly much more than there was a few years before?
What do you say to critics who say, when we all left, when everybody --- when everybody, all the American troops left, we created a void that allowed ISIS to grow and create that caliphate?
JOE BIDEN: I was either in the country -- I've been in, I think 26 times, well over 20 times into Iraq. And during this period as vice president and the year my son was there, I was there a lot. I guess I've been in eight, 10, 12 times.
There wasn't one single, solitary leader, including the Barzani and the Kurds, who would vote in the core of their parliament to allow the Status of Forces Agreement. Not one, because they were worried what would happen is it would be used against them politically, supporting the occupier.
http://info.msnbc.com/_news/2016/07/27/35882707-morning-joe-news-joe-biden-says-the-democratic-party-overall-hasnt-spoken-enough-to-white-working-class-voters?lite