In his cape-wearing turn as a pimp in his undercover ACORN sting, James O’Keefe had cast himself as a new kind of conservative crusader, using the Internet bullhorn to tear down what he saw as liberal prejudices.

But Mr. O’Keefe’s arrest for allegedly trying to tamper with the phones of Sen. Mary Landrieu (D) of Louisiana Monday will have consequences, not only for O’Keefe but also for the new brand of conservative muckraking he sought to pioneer.

That movement has taken a hit, and the incident may chill future investigative efforts against liberal targets, some conservative journalists say.

Indeed, many conservatives who had lauded O’Keefe’s work on the ACORN story - in which he showed that some workers of the left-leaning community organizing group were willing to help prostitutes avoid taxes - distanced themselves from the video-producer.

Michelle Malkin said O’Keefe got “carried away.” Fox News commentator Glenn Beck said O’Keefe had entered “Watergate territory.”

Others went further, suggesting that O’Keefe was willing to go to extraordinary lengths to incite a revolutionary fervor.

"It turns out [O'Keefe] is a lot more like Che Guevara than Woodward and Bernstein," says Steven Schier, a political science professor at Carleton College in Northfield, Minn.

Controversial but effective

Until now, O’Keefe’s tactics were borderline ethical, but undeniably effective, media experts say. In attacking ACORN — an organization created to help the needy, O’Keefe turned on its head the classic journalistic maxim: comfort the afflicted and afflict the comfortable.

The result was lots of Internet traffic, TV coverage, and even action in Congress, which stripped ACORN of federal funding.

But O’Keefe’s alleged phone-tampering attempt at Senator Landrieu’s office at the Hale Boggs Federal Building in New Orleans goes too far, says the Leadership Institute in Arlington, Va., which aims to counterbalance the perceived left-leaning bias in the media and where O’Keefe had worked and trained.

“There is a responsible way to creatively generate a story or an incident which challenges the left in an ethical, yet aggressive way,” Steven Sutton of the Leadership Institute, told Politico. “Then there’s the other way, where you cross the line - and we teach people not to do that - and you expose yourself, whatever organization you’re affiliated with, and the people that you’re associated with to a deserved and justified backlash.”

MediaMatters, the liberal media watchdog group, took a predictably harder line on O’Keefe and the movement he came to symbolize. “Vilification is the driving force and facts are optional,” Eric Boehlert writes.

Headed for trouble

O’Keefe was certainly ambitious. The topic of a now-canceled speaking appearance in Utah was "[O'Keefe's] national expose of ACORN's unethical behavior, his changes in Congress, and how [he will] inspire our party's passion for a grassroots comeback."

“Don't just respond to news, but actually create your own headlines,” O’Keefe said in a recent interview posted at a website affiliated with the Leadership Institute.

But he dropped clues that he knew that his passion for conservative muckraking could get him in trouble, too. He told Mr. Beck last year that he’d be willing to go to jail for a story.

In the FBI affidavit, O’Keefe admits to planning the operation and the men admit they entered Landrieu’s offices under false pretenses. The unanswered question, so far, is whether this was part of a broader Watergate-style conspiracy.

An NBC report suggests that O’Keefe was merely trying to verify allegations that Landrieu's office was being deliberately unresponsive to constituents on the issue of healthcare reform.

It has turned into a cautionary tale. “For now, let it be a lesson to aspiring young conservatives interested in investigative journalism,” wrote Ms. Malkin on her blog. “Know your limits. Know the law. Don’t get carried away. And don’t become what you are targeting.”