Let's be clear here. Leaders that are true to their beliefs don't need teleprompters or other cues to allow them to speak proficiently.
If Obama was giving a speech to his comfort zone, socialists, he would have less need of a teleprompter than if he was giving a speech to a more conventional crowd, let alone conservatives in the mix.
Conversely, if I was trying to speak to socialists on their level without the speech stutterings, etc, I myself would need a teleprompter.
The bottom line: You look at someone like Sarah Palin who is more comfortable with conservative tenets and debates on that level, she has no need for prompters. As long as Sarah is not trying to convince the moonbat wing of the democrat party (which, nowadays, pretty much consists of the whole democrat party), then she won't sound stuttering.
So to that end, in a debate, there is no way that Obama would come close. The only problem would be in how the debate was conducted, in which the bias could heavily be favored toward Obama.