When Mitt Romney was asked at a New Hampshire town hall in June 2011 about climate change, he probably did not think he was taking a risk by admitting that it is happening. “I believe based on what I read that the world is getting warmer,” said Romney. “Number two, I believe that humans contribute to that…. And so I think it’s important for us to reduce our emissions of pollutants and greenhouse gases that may well be significant contributors to the climate change.”

The science on the subject is clear, and Romney had said the same in the 2008 without inviting a notable backlash. But this time was different. Rush Limbaugh, the godfather of modern conservative talk radio, reacted with horror. Romney had just demonstrated himself too credulous of science and Enlightenment reasoning to win the Republican nomination. “Bye-bye nomination,” Limbaugh intoned. “Another one down. We’re in the midst here of discovering that this is all a hoax. The last year has established that the whole premise of man-made global warming is a hoax, and we still have presidential candidates who want to buy into it!”

Limbaugh’s assertion that Romney could not win the Republican nomination was premature; Romney remains very much in contention. But right-wing voters have held Romney’s statement against him as they continue to search for a suitable alternative.

The brouhaha might seem strange to an outsider, since Romney did not actually propose to do anything about climate change. In his campaign book No Apologies, Romney dismissed cap and trade as “radical feel-good politics.” But the conservative media no longer accept objective facts—the facts themselves must now fit the right-wing narrative. Joseph Lawler, then the managing editor of The American Spectator, explained the closed-circuit epistemology as a means of guaranteeing a preferred policy outcome: “Expressing skepticism of the science behind climate change, as for instance Gov. Rick Perry has, allows candidates to assure voters that they won’t support cap and trade or carbon taxes once they’re in office.”

Sure enough, the next time Romney discussed climate change publicly, at a town hall in Dover, New Hampshire, in August, he softened his earlier comments, saying, “I think the Earth is getting warmer…. I think humans contribute to that. I don’t know by how much. It could be a little. It could be a lot.” By late October, Romney had turned into a full-fledged climate change denier. “My view is that we don’t know what’s causing climate change on this planet,” he said at a fundraiser in Pittsburgh.

This episode—the bullying of an educated executive vying to be leader of the free world into the denial of demonstrable facts—was a striking demonstration of the sway Limbaugh and his cronies in conservative media hold over Republican hopefuls. It’s a degree of influence unmatched by any entity on the left, or for that matter by issue activists on the right. (The anti-tax Club for Growth also put out a white paper attacking Romney’s climate change apostasy, but it garnered far less attention than Limbaugh did.) And as the Republican primary unfolds, the consequences of the right-wing media megaphone are clear: the ideological discipline meted out by the pundits is a big part of the reason Republican candidates are sticking so relentlessly to doctrinaire conservative positions during this campaign cycle, and why there is often so little space between them.

Limbaugh, who invented the modern right-wing talk radio format and spawned a generation of imitators, is not the only pundit who thinks he is more powerful than actual elected officials: in October, Sean Hannity invited Rep. Ron Paul (R-TX) on his radio program and spent most of the interview lecturing Paul for having had the audacity to criticize him. But Limbaugh is the only one for whom it is undeniably true. “The candidates who run afoul of Limbaugh are marked for death,” says Thomas Fiedler, dean of the College of Communication at Boston University. “Talk radio, and Limbaugh in particular, has defined what the acceptable limits are for the candidates,” Fiedler adds. “They’ve clustered themselves much farther on the right end of the spectrum.”

For the conservative media, the task of whipping Republicans into line isn’t limited to the official campaign. During the debate over health care reform, former public supporters of the individual mandate—including presidential candidates-to-be such as Newt Gingrich and Romney—abandoned their prior positions and lined up against “Obamacare.” Amid the hyperventilating about “death panels,” as the party’s prospective standard-bearers fell into line, it became politically untenable for GOP legislators to negotiate even on a bill whose roots lay in conservative proposals. The Affordable Care Act ended up passing nonetheless—and Republicans in Congress had no influence over the law.

“There were leaders who knew better, who would have liked to deal. But they were trapped,” wrote former Bush speechwriter David Frum. “Conservative talkers on Fox and talk radio had whipped the Republican voting base into such a frenzy that deal-making was rendered impossible.” Speaking to ABC’s Nightline soon after, Frum summed up the new balance of power. “Republicans originally thought that Fox worked for us,” he said, “and now we are discovering we work for Fox.”

In some cases, literally. When Gingrich, a former supporter of action on climate change, came out against the cap and trade bill in 2009, he was a paid contributor to Fox News. As with Rick Santorum, a Fox sinecure gave him a way to stay in the public eye after leaving office with low approval ratings. And Herman Cain used his talk radio show to launch his fleeting political career, which was sustained by frequent appearances on Fox and conservative talk radio.

Some might say that Gingrich still works for Fox. For all his enthusiastic sparring with “media elites,” Gingrich has kowtowed to the conservative media as abjectly as anyone. On Meet the Press on May 15, Gingrich aptly characterized Rep. Paul Ryan’s (R-WI) plan to eliminate Medicare and replace it with vouchers for seniors to buy health insurance as “right-wing social engineering,” adding that it was “radical change” that is “too big a jump.”

The conservative media instantly vilified Gingrich as a traitor. “There is no explanation for it,” Limbaugh said. “It cuts Paul Ryan off at the knees.” Gingrich appeared on Sean Hannity’s radio show to do damage control but found himself on the defensive. Meanwhile, Ryan appeared on Laura Ingraham’s radio show to join in the Gingrich bashing. By May 17, Gingrich was groveling. “I made a mistake,” he said to Greta Van Susteren on Fox News. “And I called Paul Ryan today, who’s a very close personal friend and I said that. The fact is that I have supported what Ryan has tried to do on the budget.”

While there are undeniable heavyweights, like Limbaugh, in the conservative media machine, this swift discipline doesn’t happen as the result of a top-down directive. It is more accurate to think of the conservative media ecosystem as a giant circular feedback loop. Conservative talk radio’s rise in the late 1980s and early 1990s begat the creation of Fox News in 1996. Conservative blogs in turn arose in the last decade. Bloggers and their commenter communities listen to talk radio and watch Fox News, while Fox and radio hosts read conservative blogs, websites, and newspapers such as The Washington Times and New York Post. Thus conservatives in print, online, and on-air create and promote each other’s memes. The course of the right-wing obsession at a given moment, from the “Ground Zero Mosque” to Herman Cain, is often bottom-up as much as it is top-down.

The partial exception is conservatives in the elite print and online media: a few magazines such as National Review and The Weekly Standard, along with The Wall Street Journal editorial page and columnists in The Washington Post such as Charles Krauthammer. Although they appear on Fox and talk radio, members of this crew generally get their news from more mainstream sources, and from each other. Though their political agenda often aligns closely with their fellow travelers, having one foot in the wider world means they will occasionally admit a candidate has left the reality-based community.

“This is an important dichotomy, between activist conservative pundits and journalists who have a conservative viewpoint,” says Matt Lewis, an independent-minded blogger for The Daily Caller, Tucker Carlson’s conservative website. “One side says you should tell the truth and report things and the other says, ‘Not if it hurts our side.’”

Nonetheless, the power of partisan message enforcement only works in one direction—rightward. Consider Rick Perry’s assertion that it would be “almost treasonous” for Federal Reserve Chairman Ben Bernanke, originally an appointee of George W. Bush, to attempt monetary stimulus a mere 16 months before an election, coupled with a vague threat of mob violence should Bernanke visit Texas. Most conservative pundits gave Perry a pass. Karl Rove, who has a longstanding personal grudge with Perry, took issue with the comments on Fox News. But the rest of the conservative choir stayed mostly silent; Perry was not forced to backtrack to appease outraged talk radio hosts. He never apologized.

Or consider Herman Cain’s shocking promise to deter illegal immigrants by building a deadly electrified fence topped with barbed wire on the U.S. border with Mexico. In one instance Cain added that he would consider using military troops “with real guns and real bullets” on the border. The next morning on Meet the Press Cain claimed it was a joke, though the context of his speech and the crowd’s reaction at the time had suggested nothing of the sort.

But that was good enough for conservative outlets, which credulously reported Cain’s spin, if they covered his remarks at all. The Weekly Standard managed to do an entire item on Cain’s Meet the Press appearance without mentioning the issue. Meanwhile, Eric Erickson of the blog Red State wrote posts lambasting “uptight people” for not getting the joke. “Herman Cain has done something we all owe him a debt of gratitude for doing,” wrote Erickson. “He has singlehandedly revived a stereotype many people thought had been forgotten—the humorless liberal.”

Leftward deviations from the party line, on the other hand, are swiftly punished. The issue of immigration provides a perfect case study in the contrast. Just two weeks before the Cain episode, when Perry said that those who disagree with his decision to let illegal immigrants brought to America as children attend Texas public universities at in-state rates “don’t have a heart,” the condemnation in the conservative media was swift and furious. “This isn’t even an immigration issue any more,” wrote Mark Krikorian in a typical blog post for National Review. “This is the same ‘kinder, gentler,’ ‘compassionate conservatism’ contempt for the grassroots that animates much of the Republican party establishment. Perry can shoot coyotes from now till doomsday and he’s never going to live this down.” When Perry inevitably retreated, telling the conservative website Newsmax.com that he had been “over-passionate” in his word choice, blogger Michelle Malkin complained that Perry did not actually use the word “sorry.”

Meanwhile, the speed with which conservative pundits can force a candidate to reverse himself on a relatively moderate view continues to accelerate. On the morning of October 25, while campaigning in Ohio, Romney was asked whether he supported Gov. John Kasich’s anti-union referendum. Not wanting to alienate any voters in a general election swing state, Romney punted. “I am not speaking about the particular ballot issues,” Romney said. “Those are up to the people of Ohio.”

By early afternoon the conservative press was apoplectic. “If Romney can’t endorse this common sense reform at the state level, why should conservatives believe he will fight against government unions at the federal level,” wrote Conn Carroll of The Washington Examiner. “This is a huge freaking deal,” wrote Erickson, adding a warning to Romney: “Typically, when a politician stands for nothing except his own election, he winds up not getting elected.” For the rest of the day Romney’s campaign tried to stay away from the issue. “Gov. Romney believes that the citizens of states should be able to make decisions about important matters of policy that affect their states on their own,” his campaign spokesman told National Review.

But by the next day it was clear this evasion wouldn’t fly. At a rally in Virginia, Romney abjectly apologized for straying from his partisan marching orders. “I’m sorry if I created any confusion in that regard,” he said. “I fully support Gov. Kasich, I think it’s called Question 2, in Ohio. Fully support that.” Limbaugh boasted, with reason, that he and his friends were responsible for this turn of events. “Daniel Henninger of The Wall Street Journal wrote a piece about Romney and said the jury’s still out,” said Limbaugh. “He said Romney is going to have to be pushed via competition, outside pressure, what have you, is going to have to be pushed to the right, and this I think is an example of what Henninger meant. Romney being pushed to the right. We’re always happy here at the EIB Network to help clear up any confusion in political candidates’ minds.”

The conservative media message discipline raises two questions: Is it good for conservatives, and is it good for journalism? The first point is debatable; liberals often wish they had a mechanism for whipping dissident Democrats into line akin to the Fox effect. But it is undoubtedly bad for journalism, even opinion journalism. There’s nothing wrong with journalism conducted through an ideological prism, but at its best such reporting and commentary upholds the same values of mainstream journalism. It pursues truth, offers both sides of an argument (albeit before reaching a conclusion), and expands the realm of discourse. Rigid partisanship, by contrast, places truth below political ends, ignores inconvenient facts or analysis, and constricts the parameters of debate. To the extent that conservatives want to keep Republicans in line, the conservative media serves them well. But insofar as conservatives want an ideological media that informs and expands their understanding of the world, it does not.

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Ben Adler covers climate-change policy for Grist and is a contributing editor for CJR