Madefix

Im in a bit of a conundrum and hope that someone can offer some advice. I was considering two chemistry PhD programs to start in fall of 2013 , UO and FSU. On April 15th, out of necessity, I picked the UO. I have found a professor who is willing to take me in their lab early and start research early over the summer. However, I have had extreme doubts about my decision about attending UO and instead believe I should attend FSU. FSU's offer is still valid for this upcoming fall, however it is conditional on having UO give me an official release. My question is this: Can I still reasonably ask UO for the release and will they give it to me? I haven't started there yet nor have I received any funding/grants/stipends, etc. And if I do ask and they say no, does that put me in a very awkward position? I already have a masters, so getting an MS and transferring isn't really an option. I see that its damn near impossible to switch programs once you start. My back up plan is enlistment if grad school doesn't work out.