A groundbreaking study of news coverage of the center-right Tea Party finds that MSNBC has gone out of its way to malign the intelligence and ideology of the movement and its members while Fox News has acted as a "guard dog" to protect it from liberal attacks.

In the first-of-its-kind study published in the authoritative International Journal of Press/Politics, two scholars reviewed stories about the Tea Party on MSNBC, Fox, CNN and from the Associated Press and found that only CNN and the AP provided largely unbiased coverage focused more on the movement's politics and policies than personalities.

"MSNBC was much more likely to malign the perceived intelligence, character and ideological position of the movement's members and characters," wrote Joshua Scacco of the University of Texas and David Weaver of Boise State University. Meanwhile, they added, "Fox News serves as a guard dog against other media channels, particularly those on the left."

Focusing mostly on the nightly broadcasts where hosts are more pointed and opinionated, their study found that MSNBC portrayed the Tea Party as oddballs in a divided Republican Party. They reported that the network went out of its way to use language that marginalizes the Tea Party, which succeeded in electing dozens of House members in 2010.

"MSNBC programs were more likely to portray the Tea Party as idiots, argue that within-movement public opinion was fractured, and represented it as fake public opinion," said the study provided to Secrets. "MSNBC engages in more marginalization."

Fox, meanwhile, used language and stories less to cheer on the movement than to protect it from attacks like those on MSNBC. Fox's "emphasis," they said, was "on inoculating the Tea Party from attacks."

CNN and AP also focus on issues raised by the Tea Party. "By prominently listing policy issues, CNN justified the movement's actions as the product of legitimately held grievances," said the authors.