New Jersey Gov. Chris Christie is expert at playing good cop, bad cop. The twist is that he plays both roles himself.

Despite being a Republican governor in a blue state that has elected a solidly Democratic-controlled Legislature, Christie has earned 50-percent-plus approval ratings in a spate of recent polls. This record, combined with his bold approach and a larger-than-life demeanor, has attracted national media attention. Christie has been given a high-profile role as a surrogate for Republican presidential candidate Mitt Romney as well as an unofficial spot near the top of the list of potential vice presidential nominees.

So what makes Christie tick? In a series of interviews in Trenton, political observers painted a picture of a talented politician with razor-sharp political instincts -- but also someone whose bluntness sometimes jeopardizes his agenda.

One need look no further than his altercation with Assemblyman Reed Gusciora. Irked by barbed criticism from Gusciora about his stance opposing gay marriage, Christie called the assemblyman -- the state's first openly gay lawmaker -- "numbnuts." Facing aggressive questioning by Rutgers law student Bill Brown at a public meeting, Christie called the former Navy SEAL an "idiot." And blasting an unfavorable budget projection from the state's official, nonpartisan legislative analyst, Christie called him "a joke," a "handmaiden" for the majority and "the Dr. Kevorkian of numbers."

But then there's the Christie that knows how to turn on the charm and have fun. Take the self-deprecating web video that Christie, a Republican, recently collaborated on with his Democratic rival, Newark Mayor Cory Booker -- a video that was so amusing it quickly went viral.

"The guy is direct and humorous, a refreshing combination for many people in his audience," said Peter Woolley, a political scientist and director of the PublicMind Poll at Fairleigh Dickinson University.

At a time when many voters are down on politics as usual and the tendency of politicians to offer only empty, focus-group-tested statements, Christie's willingness to speak from the gut has appeal, particularly in contrast to his predecessor, Democrat Jon Corzine, whose speeches were considered less than electrifying.

But rhetoric is one thing and legislative accomplishments are another. On that score, Christie has chalked up some tangible achievements.

The accomplishment that even his skeptics give Christie significant credit for was his shepherding and signing of a bill that required public employees to pay more for their pensions and health coverage. The bill represented the apex of cooperation between Christie and Democratic Senate President Stephen Sweeney.

Sweeney had made the issue a priority even before Christie was elected in 2009. After Christie's election, he and Sweeney won over the more hesitant Democratic Assembly Speaker Shelia Oliver on the way to securing bipartisan backing in the Legislature for the measure, over the staunch opposition of Democratic-leaning public employee unions.

Christie has also succeeded in expanding charter schools, and he receives a degree of credit for his work on fiscal matters. "He has gotten the budget under control without raising taxes, something his two elected predecessors also promised to do and did not," said Woolley, referring to Corzine and Democrat James McGreevey.

Brigid Callahan Harrison, professor of political science and law at New Jersey's Montclair State University, also points to efforts by Christie to rein in public authorities that have been "hotbeds of cronyism. No New Jersey governor in modern times has exercised power as deftly and assertively as Chris Christie," Harrison said.

Underlying many of Christie's legislative successes is the support of Sweeney, whose moderate profile and connection to blue collar workers -- he was the general organizer of the International Association of Ironworkers -- has meshed well with the governor's agenda.

While the Christie-Sweeney relationship has run hot and cold -- one budget maneuver by Christie so enraged Sweeney that he called him a "rotten prick" -- there have been enough periods of "bromance" between the two men to mold an effective partnership.

"This is the only remaining political machine state in which the gears of both machines mesh smoothly," said Rutgers political scientist Ross Baker. "Early in his term, Christie entered into a pact with the Democratic bosses of both South Jersey and North Jersey, which left the independent and liberal Democrats in the Assembly pretty toothless. Those who uncritically embrace bipartisanship should take note of the oddest of bedfellows in New Jersey cohabiting."

Christie's policy record is hardly infallible. In fact, observers agree that his biggest slip-ups have stemmed from unforced errors.

In 2010, Christie declined to reappoint state Supreme Court Justice John Wallace Jr., who was a respected and pioneering African-American jurist in the state, even though Wallace would have only had about 18 months to serve before the mandatory retirement age took effect, at which point Christie could have chosen Wallace's successor. The move not only offended Democrats, who saw it as needlessly mean-spirited, but irked Sweeney in particular, who was close to Wallace. His picks to fill Wallace's seat and another vacancy to the court were summarily rejected in the state Senate.

Another contentious issue has been a Christie-backed plan to merge Rutgers University-Camden with Rowan University. "Christie had forged cozy relationships with some of the state Democratic power brokers, and the policies that have resulted from those alliances, such as the proposed Rutgers-Rowan merger, have been partially driven by special interests and have sometimes proven unpopular both in the Legislature and at the grass-roots level," said Harrison of Montclair State.

The powers granted to New Jersey's governor make the post one of the most powerful in the nation, and Christie has used his authority to the hilt.

Christie, a former U.S. Attorney, "understands the power that goes with his office and is not reticent to reward and punish people," said Cliff Zukin, a public policy and political science professor at Rutgers University. "He makes it costly to oppose him. His model is plea bargaining in the legal system -- he doesn't give things away. He tries as hard as he can for the stuff he really wants, doesn't show his hand and you only know what he's really willing to accept at the last minute."

"He knows all the tools and knows how to use them," said Tom Wilson, a former state Republican Party chairman who was a consultant to Christie as well as then-Govs. Christine Todd Whitman and Donald DiFrancesco. "He has a deep appreciation that political capital does not have a long shelf life, and that it's best appreciated by spending it."

David Redlawsk, a Rutgers political scientist, credits Christie's political shrewdness. "He acts like he simply won't compromise, but in reality he has signed on to a number of them. In other words, it's complicated."

One sign of this shrewdness is Christie's success in harnessing New Jersey's unusual media situation to his advantage. Unlike most states, New Jersey is primarily served by out-of-state broadcast outlets, based in New York City and Philadelphia. This means two things. First, only a few media outlets, such as the Newark Star-Ledger, make covering New Jersey politics a top priority. This allows Christie to operate with relatively little scrutiny from down-in-the-weeds, home-state reporters. Second, Christie's proximity to the media capital of New York City has helped raise his profile nationally.

Seeing Christie on a program like MSNBC's Morning Joe, NBC's Meet the Press or CBS' 60 Minutes "validates people thinking that he's doing a good job," Wilson said. By contrast, there's no Democratic figure in the Legislature that can hold a candle to Christie in media attention, Wilson said. The one Democratic star is a mayor, Booker, though it's unclear whether, or when, he will seek higher office.

Polls suggest that overall, the Christie show has been playing well in the state, but not without prompting a degree of polarization. Hard-core and ideologically liberal Democrats tend not to be falling for him. In the just-released Rutgers-Eagleton poll, Christie's approval rating was 79 percent positive, 12 percent negative among Republicans, compared to 27 percent favorable, 62 percent unfavorable among Democrats. The key for Christie is that he has a 55 percent positive, 32 percent negative rating among independent voters.

"His crossover appeal lies largely with white males," Harrison said. "There is consistently a large gender gap in his approval ratings. He does not enjoy crossover appeal with staunchly Democratic voters, particularly those from union households."

Christie's voter support is generally built on core Republicans, combined with the backing of independents who appreciate his seeming effectiveness and straight-shooting persona, observers said. Maintaining his appeal in a Democratic-leaning state has meant occasionally taking positions more moderate than many in his party, such as on immigration. He also nominated a Muslim for the bench and has advocated for drug courts, which take a more treatment-oriented approach.

Christie's biggest positioning challenge in the months ahead may be to reconcile his growing prominence in the national GOP -- including the possibility that he could get the vice presidential nod -- with the need to keep voters back home from turning on him.

Polls still show New Jersey in the Democratic camp for the presidential race, and the national Republican Party is a whole lot more conservative than New Jersey voters generally. It's possible that Christie could weaken his standing at home if he goes too far out on a limb with Republican orthodoxy. (Romney experienced that popularity decline in Massachusetts toward the end of his one term in office.)

"Christie has embraced several policies -- canceling a tunnel to New York and cutting funding for Planned Parenthood -- that were clearly designed to pander to the national conservative GOP constituency and that were unpopular here in the state," Harrison said. Christie has also steadfastly refused to back same-sex marriage.

"He's sending the state in the wrong direction," said Gordon MacInnes, a former Democratic state legislator who's now president of New Jersey Policy Perspective, a Trenton think tank. "But I can't say he's not effective at it."

Power Struggle: Governors and the Legislatures

Chris Christie may be taking a particularly outspoken approach to governing, but he's far from the only governor who faces a Legislature fully controlled by the opposite party. Interviews with political experts in these states suggest that governors in this situation are using a wide variety of approaches.

For instance, Minnesota Gov. Mark Dayton, a Democrat, and the GOP Legislature have repeatedly clashed, leading to "the only state government shutdown in the nation in 2011, followed by a budget deal that favored the GOP as the governor relented under public criticism over the lack of services due to the shutdown," said Steve Schier, a political scientist at Carleton College in Northfield, Minn. Dayton fared better in 2012 by exploiting GOP divisions over a new stadium for the NFL's Vikings.

In New Mexico, clashes have been common. A political action committee led by backers of Republican Gov. Susana Martinez went so far as to spend six figures on efforts to defeat more liberal Democrats in state House and Senate primaries. On primary day, the PAC was successful in electing moderate Democrats in seven out of the eight targeted races. The intent was to shape a Legislature more open to collaborating with Martinez.

By contrast, at least one governor, Democrat Jay Nixon of Missouri, has worked comfortably with a Legislature dominated by the opposite party. "Nixon is not a dogmatic Democrat pushing a liberal agenda against the tide," said Ken Warren, a Saint Louis University political scientist. "His relationship with the Legislature is not hostile at all, angering a lot of Democrats who think that he should act more like a Democrat."

Meanwhile, two Democratic governors - New Hampshire's John Lynch and North Carolina's Bev Perdue -- have largely been overtaken by events, observers say.

"In New Hampshire, the reform push is coming from the Legislature, and Lynch has not had enough legislative backing to keep several of his vetoes from being overridden," said Andrew E. Smith, director of the University of New Hampshire Survey Center. James Pindell, the political director at WMUR-TV in New Hampshire, puts it bluntly. He calls Lynch - who is not running for another term -- "insanely popular and insanely irrelevant."

North Carolina's Perdue has also foregone a chance to run again, making her virtually irrelevant as well.

"Ever since she announced her decision at the end of January to not seek another term, she's clearly taken a backseat in the legislative process," said Jonathan Kappler, research director for the pro-free-market North Carolina Free Enterprise Foundation. "At this point, the more interesting political and governing questions in Raleigh are the differences between the GOP leadership in the Senate and the GOP leadership in the House, and the potential political aspirations of those leaders."

The most intriguing echo of Christie's outspoken approach -- from the opposite partisan direction -- involves Montana Democratic Gov. Brian Schweitzer.

"His approach has been one of open aggression and battle," said one political observer in Helena. Schweitzer, who had already nurtured a reputation for outspokenness earlier in his term, took the approach to its logical conclusion when he made several branding irons featuring the word "veto." He had a public ceremony on the front lawn of the Capitol where he took about 20 bills and branded them with the red-hot iron.

"This stunt no doubt bolstered Schweitzer's popularity in the minds of many, and his aggressive style I think has served him well with the public," the source said. "People like a politician who takes a bold public stance, apparently on principle." Still, his seeming disdain for lawmakers helped derail a $100 million bonding bill, raises for state employees and additional university funding that led instead to a big tuition increase.

"He pissed a lot of people off, and, in the long term, he's hurt the reputation of the Legislature," the observer added. "Not a good thing."