Consider that last month, Huckabee led the way at 16% in CNN's poll, followed by Trump at 14%, and then Romney (13%), Palin (11%), and Ron Paul and Gingrich (10%.) Giulani was not included in that survey. This month, Giuliani topped all comers at 16%, followed closely by Romney (15%), Palin (13%) and Ron Paul (12%), all of whom fell within the 4.5% margin of error for first place.
Tim Pawlenty, Gary Johnson and Jon Huntsman fell in at the bottom of the list, all candidates who, as of mid-March, were unknown to over half off all Americans; over seven in ten adults said they didn't know who Huntsman was in a March poll.
In short, the names voters knew are the names that they chose.
CNN's results closely resemble those from a Gallup poll released Thursday, in which Romney and Palin claimed the top two slots that Huckabee and Trump had held in April. Giuliani was not polled in that survey.
Even the simple fact that Trump once dominated the race is a sign of how undefined the field is. Trump came out of the nowhere to, in about a month, suddenly top the entire field by as much as nine points, largely because he kept popping up on every TV station. And in an even shorter time than he rose to the top, Trump plummeted back down when his signature issue -- claiming that Obama wasn't born in America -- was diffused by the release of Obama's long-form birth certificate.
The CNN poll was conducted May 24-26 among 473 adults nationwide. It has a 4.5% margin of error.