On a Friday night in January, Bill Maher made an off-kilter joke about mass shootings. By the following Monday, Tamara Holder was summoned to The Sean Hannity Show, where she has built a following playing an extreme form of devil’s advocate for Fox News. Sandwiched between two right-wing pundits and the show’s brash host, the progressive Holder held her tongue and rolled her eyes while the rest of the panel bantered. Holder may seem like an odd choice for a network that’s been called “the PR arm of the GOP.” But the Chicago-educated attorney, who has collaborated with the Rev. Jesse Jackson, is a bone fide Fox News correspondent, and she sits among an increasingly prominent group of news analysts at the conservative network—those on its left wing. Call them punching bags, foils, or the engines of honest debate, Fox’s flock of liberal commentators lay out the nation’s partisan battles in real time—on a network where coastal elites would argue that no dissenting voices exist.

Since Holder signed with Fox in 2010, the charismatic brunette has made a name for herself hashing out the kind of controversies that spring from cable’s niche airwaves into the mainstream press. Fox colleagues and guests have slammed her haircut, calling her a “Farrah Fawcett wannabe.” Once, in a discussion turned shouting match over whether Attorney General Eric Holder committed perjury, conservative radio host Bill Cunningham ordered Tamara Holder to “know your role and shut your mouth.” “My role as a woman?” Holder shot back. (The network later apologized for Cunningham’s comments.) That Monday, on Sean Hannity, while her peers picked apart Maher’s remark—he’d suggested that conservatives match a gay wedding recently staged at the Grammys “by having a mass shooting at the Country Music Awards”—Holder sat waiting for a break in the chatter. It took two interjections of “let me finish” before Holder could break in. “They finally let me speak,” she told me, a few hours after she finished taping the segment. “They had to. Otherwise they knew I would stand up and choke them.”

The ranks of liberals welcomed one more in February, when Fox hired James Carville, formerly the left flank of Crossfire and once the lead strategist for Bill Clinton. Unlike many of Fox’s liberal pundits, who’ve built their public personas playing David to a team of conservative Goliaths, Carville has been one of television’s most visible progressives for decades, often debating his wife, the conservative political consultant Mary Matalin. (The Washington Post covered his move to Fox with the headline “Pundit James Carville prepares for further torture as Fox News contributor.” ) If there were any doubts about whether Fox just looks for middling also-rans to do the left’s bidding, the arrival of Carville should resolve them.

Though MSNBC has a handful of moderate conservatives—namely Morning Joe’s Joe Scarborough—Fox stands out for the prominence it awards its on-air naysayers, many of whom occupy regular roles on the network’s most popular shows. Personalities like Kirsten Powers, who made her way up through the Clinton administration and now goes head-to-head with Bill O’Reilly on nationalized healthcare (she’s for it), the death penalty (against), and the Iraq war (against). Their screen relationship is one of playful respect; when their debates grow heated, O’Reilly warmly calls her “Powers.”

Why would liberals in good standing risk becoming Democratic Party outcasts by going to work for Fox? And why does Fox spend good money acquiring them? The first question is easier than the second. Tamara Holder says she’s often asked how a person who once wrote for GrassRoots, a medical marijuana magazine, found herself on a network geared toward the country’s most faithful conservatives. Her one-word answer: “ratings.”

The harder question is the one directed at Fox’s motives. Ratings, of course, would be the logical answer here, too. But it’s possible that’s not the sole explanation.

Alexis Sobel Fitts is a senior writer at CJR. Follow her on Twitter at @fittsofalexis.