As Republican presidential contenders brace for Wednesday's CNN-YouTube debate, the executive in charge of the event is unapologetic about his decision to put mainstream journalists in charge of deciding which user-contributed YouTube videos the candidates will actually face on the air.

For all the talk about online voter empowerment, the web is still too immature a medium to set an agenda for a national debate, says CNN senior vice president David Bohrman.

"If you would have taken the most-viewed questions last time, the top question would have been whether Arnold Schwarzenegger was a cyborg sent to save the planet Earth," says Bohrman, the debate's executive producer. "The second-most-viewed video question was: Will you a convene a national meeting on UFOs?"

Thus, instead of using an online voting system to select video questions, CNN's journalists are plowing through the contributions this week. CNN will air the final 40-or-so selected questions Wednesday (8 p.m. EST) when the Republican presidential candidates take the podium in St. Petersburg, Florida – submitting to a debate format Democratic presidential candidates went through in July.

CNN's YouTube-enabled presidential debate is one of several mainstream media experiments in voter-candidate interaction that have emerged this election cycle – and faced mixed reviews. The Huffington Post teamed up with Yahoo and online political newsmagazine Slate in September to allow netizens to pick preselected questions for the candidates, which were then posed by PBS talk show host Charlie Rose. Videos of the recorded interviews were posted on the web. But the interactive element was little more than an on-demand cable-television-like offering, and not a true two-way conversation between voters and candidates.

In a more successful stab at voter participation, MTV and MySpace teamed up to modernize the traditional town-hall format by enabling the online community to submit questions by instant messenger and to vote in real time on the candidates' performance. Though the process has suffered from technical glitches, the effort won praise as an effective way to broaden the scale of interaction between the candidates and the public. So far, Democrats John Edwards and Barack Obama have participated. Republican presidential candidate John McCain is next on Dec. 3.

With its YouTube collaboration, CNN is one of the first television networks to attempt to meld the televised presidential-debate format with an online social networking tool. But the news network has received a steady barrage of criticism for keeping a tight grip on the decision to select or reject particular video questions for the event.

An author at The Huffington Post blasted CNN on Monday for its decision to weed out questions for Republican candidates that the producers suspected were submitted by Democrats.

"The notion that the CNN-YouTube debate represents a grass-roots triumph of the internet age is laughable," wrote Marty Kaplan, a research professor at the University of California's Annenberg School for Communication. "The 4,000+ videos are pawns; the questioners are involuntary shills, deployed by the network producers in no less deliberate, calculating and manipulative a fashion as the words and stories fed by teleprompters into anchors' mouths."

But Bohrman, a 53-year-old technology geek and network TV news veteran, says allowing internet users to vote on which videos to air would reduce, not enhance, the quality of the debate – a lesson he says he learned during a brief stint at the doomed online media company Pseudo.com.

"Guess what, there are troublemakers," says Bohrman. "When I was at Pseudo, and we ran live video chats, we had (people typing) 'Fuck You' in 98-point-type, which appeared on the screen."

He's also concerned that the questioning could be manipulated. "It's really easy for the campaigns to game the system," he says. "You've seen how effective the Ron Paul campaign (supporters) have been on the web – you don't know if there are 40 or four million of them. It would be easy for a really organized campaign to stack the deck."

Community-chosen videos would also rob the debate of spontaneity, because the candidates would know well in advance what question they will be asked.

But in the end, Bohrman just doesn't trust people on the internet to pick the interesting questions. A recently launched project by TechPresident called 10 Questions allows users to vote up or down on video questions that will then be sent to the presidential campaigns, but he's not impressed with the results.

"You look at 10 Questions, and some of the questions are interesting," Bohrman says. "But some of them are completely irrelevant and not interesting, and then it's just another artificial Kabuki dance."

Micah Sifry, co-founder of TechPresident, which is running the project, says that Bohrman is oversimplifying.

"There are all kinds of creative ways to invite community input that would still allow for editorial judgment, too," Sifry says. "For example, CNN could use the 10 Questions model – we'd be happy to collaborate with them – to involve the community in parsing questions and then promise to use half the questions picked by the community, with the other half picked by his political team."

For his part, Bohrman sees the journalist's role in the election process as a facilitator. The goal at this stage of the process is to help voters on either side of the aisle try to distinguish key differences among their parties' candidates before they vote in the primaries, he says.

"We want a really Republican debate that underscores the differences among the candidates," he says.