The leak of a major ad campaign proposal that would go after President Obama's past relationship with the controversial Rev. Jeremiah Wright has had both Republicans and Democrats -  even the billionaire who had requested the pitch - trying to distance themselves.

Yet dirty tricks, negative campaigning and personal attacks are all part of modern campaigning.

John McCain forbade his staff from bringing up Wright in 2008, although some in his campaign objected, most notably Sarah Palin. This recent proposal from Republican strategists, including GOP ad man Fred Davis, first reported by The New York Times, says it will "do exactly what John McCain would not let us do." The 2008 GOP nominee didn't want to link Obama to Wright for fear of being labeled a racist and because he had felt the pain of negative attacks. In 2000 he was accused of fathering a black child with a woman not his wife.

This cycle there were fears of third party groups trying to malign Romney for his Mormonism, although that hasn't happened, not even in places like Iowa and South Carolina, where personal attacks are legion. E-mails about the presumptive GOP nominee's religion floated around South Carolina during the last campaign, but not this time around.

The risk vs. reward of negative personal attacks is a fine line: You could be successful (the attacks McCain suffered in 2000 may very  well have led to his loss in South Carolina to George W. Bush) or there could be severe backlash from voters  turned off by the tone.

Ed Rollins, longtime GOP consultant behind many famous  Republican ad campaigns and successful GOP candidates, said there is an "art form to the negative ad" and it's important to use a "scalpel, not a baseball," adding he believes there would probably be voter backlash to the ad campaign described in the proposal.

"If you do it, you have to do it very carefully, accurately, and it has to be believable," said Rollins, who earlier this year worked on Michele Bachmann's presidential campaign, but they parted ways and Rollins publicly criticized her. 

Rollins said negative ads should "be part of a narrative" that consists of "three or four ads" that define the candidate as "unacceptable and remind people of what they don't like."

Rollins said ad campaigns that are "breaking fresh ground or over the top usually don't work," and the ones that are most effective start out with a positive, believable line.

The concept of the SuperPAC, though, does seem to protect the candidate to a certain extent. They cannot coordinate with the campaign or candidate and it doesn't say "paid by" the candidate's name at the end, making the person behind the ad not as clear as if the campaign itself was running negative ads.

Of course that can be dangerous for the candidates, as they have no way to control what is being done on their behalf.

An aide with one of the primary campaign SuperPACs who did not want to reveal his identity negatively discussing SuperPACS said the "inherent danger" in them "is that campaigns can easily lose control of what message is communicated and the timing of each message."

"Outside organizations have a built-in bias for controversy and the Hail Mary type message because that attracts donors.  Campaigns, on the other hand, have to bear the burden and backlash and have November on their mind," the SuperPAC staffer said.

"The system we have is imperfect but better than a regime that limits free speech," added the staffer, referring to the Citizens United Supreme Court case, which made these kind of political action committees open to unlimited donations legal.

A 2010 Wesleyan Media Project study revealed that that was the year of the most negative ads in recent history; a study this month shows presidential ads are 7 0 percent negative in 2012, up from nine percent in 2008.

A Dartmouth study showed a group two negative ads with the same content, one paid for by the fictional candidate and the other by a fictional SuperPAC group. Although there was no evidence anyone was persuaded, there was more backlash against the candidate when the candidate's name was used.

Rick Tyler, who runs the still-not-defunct pro-Newt Gingrich SuperPAC "Winning the Future," thinks the Citizens United ruling was too narrow and unlimited, and that transparent donations should be able to go directly to the campaigns.

"The current system is an abomination," Tyler said.  "It's an affront to a free people … because we have limited the candidates to speak for themselves and shape their own message. If we did that, these third party efforts would be obsolete."

"It's also true that millionaires and billionaires don't make the best political tacticians," Tyler added, referring to the sponsor of the proposal to attack Obama, Joe Ricketts, founder of  TD Ameritrade.

In Iowa, Gingrich got hammered by Romney's superPAC and although it helped Romney, Tyler acknowledged there is "always risk of a backlash" with negative campaigning.

Rick Santorum's SuperPAC, which is now his leadership PAC as well, ran negative ads against Romney in the primary, comparing him with Obama.

Stuart Roy, who ran communications for the pro-Santorum super PAC, The Red, White, and Blue Fund, called Fred Davis "one of the most creative minds in the political ad business," but warned there is usually a lot of back and forth before a concept is settled on.

"The challenge is for the client to separate the good ideas from the duds," Roy said.  "It appears this was the latter not the former and ended up on the cutting room floor. In the normal course of events you may discuss dozens of approaches before you settle on the direction of the message."

It's that back and forth that can prevent an over-the-top, backlash-inducing ad campaign from seeing the light of day … unless it's leaked, that is.