From left to right: White House Communications Director Dan Pfeiffer; Deputy Communications Director Jen Psaki; Senior Adviser David Plouffe; and Press Secretary Jay Carney stand in the East Room as President Barack Obama holds a news conference at the White House in Washingtonn on June 29, 2011. (Charles Dharapak/ASSOCIATED PRESS)

Welcome to the “Jen and Jay Show,” the latest iteration of the White House news briefing.

Known as “gaggles” when they take place on Air Force One, the daily briefings became a two-person road show over the summer when President Obama hit the campaign trail in earnest and petite, 33-year-old redhead Jennifer Psaki climbed aboard alongside Jay Carney to answer the growing volume of campaign-related questions coming from the press.

In the waning days of the campaign, the duo has given the briefings the feel of a vaudeville act: lighthearted and entertaining but also well rehearsed — and deadly for Republican Mitt Romney.

Straight man Carney, who is 47, a fluent Russian speaker and former Washington bureau chief for Time magazine, waxes serious about Syria or Libya — and then looks on with amusement while Psaki plays the double role of girl-next-door and tart-tongued attack dog.

Asked recently to comment on Romney’s accusation that Obama would lie during the debates, Psaki said: “If Mitt Romney were Pinocchio, his nose would be reaching from Virginia to Ohio with the number of lies he’s told.”

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A reporter even asked Carney if he was starting to feel like a bystander now that fewer questions were aimed at him. “Not at all,” Carney offered cautiously. “I enjoy listening to my colleague field your questions. It’s most comforting.”

In some ways, the Jen and Jay Show reflects the small-bore tone of the 2012 election. Obama isn’t so much promising hope or change this year; he’s asking for more time — and relentlessly tearing down Romney so he doesn’t look like a better choice. Alongside Carney’s policy-oriented spiels about the European debt crisis or the unemployment rate, Psaki spends much of her time going after Romney: scoffing at him, needling him, mocking him. She is the traveling hit woman of the Obama campaign.

Commenting on Romney’s summer trip abroad, during which he was jeered by the British press for criticizing security preparations for the Olympics, she offered: “The only person who has offended Europe more is probably Chevy Chase.”

And about PBS’s request that Obama take down an ad featuring Big Bird — in response to Romney’s suggestion that he would cut federal funding for public broadcasting — she retorted: “It doesn’t change the fact that there’s only one candidate in this race who is going to continue to fight for Big Bird and Elmo, and he is riding on this plane.”

Psaki’s one-liners are sometimes downright weird, as when she channeled David Lynch about Romney’s “lack of ideas,” which reminded her of an empty pool with “dead leaves and trees in it.” And there was Carney again, chuckling with the reporters and observing:

“I endorse language as creative and descriptive as that used by my friend and colleague.”

Moving up?

If Psaki’s style suggests a less consequential job than that of her traveling straight man, she is viewed widely as one of two top contenders to replace him, the other being Carney’s deputy, Josh Earnest. By several accounts, Carney has no plans to leave, nor is anyone pressuring him to do so. But the job of White House press secretary has a high burnout rate — and a lucrative landing pad in the private sector.

Psaki, who grew up in Connecticut and attended the College of William and Mary, is on leave from a Washington consulting firm. She has been moving in and around national politics for a decade, including stints with the Iowa Democratic Party and the Democratic Congressional Campaign Committee and as deputy press secretary for Sen. John F. Kerry’s presidential bid in 2004. She began working for Obama in 2007, mastering the art of traveling press management and then spending two years in the weeds of domestic policy as deputy White House communications director.

Psaki sat in on daily economic briefings in the Oval Office, becoming close to the president as well as some of his innermost advisers: David Plouffe, Rahm Emanuel, Robert Gibbs, David Axelrod and Valerie Jarrett. It’s no accident that so many of those people are men: Psaki is comfortable palling around with the boys, and her ability to tell jokes and talk tough in the same breath is one of the reasons they like her.

“Jen is one of the smartest, nicest and most poised people in all of politics,” said Dan Pfeiffer, the White House communications director. “She has the respect and trust of everyone she works with from the president to the press.”

If Psaki does move on to the briefing room, she would become only the third woman to do so, after Dee Dee Myers of the Clinton years and Dana Perino, George W. Bush’s third press secretary. (She’d be the fourth if you count the fictional C.J. Cregg from “The West Wing.”)

She is among a growing army of women in prominent political roles this year, including Obama’s deputy campaign manager, Stephanie Cutter, and three of the four principal spokeswomen for Romney: Gail Gitcho, Andrea Saul and Sarah Pompei. In other words, there is a very strong chance that a woman will stand at the lectern soon no matter who is elected president.

“Women are more than half of the country,” said Nicolle Wallace, communications director for George W. Bush’s White House and his 2004 reelection campaign. “I also think it sends a powerful signal about the man at the top. I give speeches all over, and I always talk about how George W. Bush’s White House wasn’t just a good place to work as a woman. It was a place ruled by women. Women in power use their power differently — more wisely and more judiciously.”

The goals of the gaggle

While the West Wing’s briefing room is staid and serious, with banks of cameras and high-octane stage lights illuminating an elevated lectern from which Carney looks down on the White House press, on Air Force One, the gaggle is little more than a klatch in the aisle of the press cabin. The reporters all stand shoulder to shoulder, and Carney and Psaki appear in the forward doorway, typically moments after takeoff. Reporters hop out of their seats, turn on their voice recorders and scrunch in close.

One reason for the intimacy is to overcome the noise of the Boeing 747’s giant engines, but another is to help brace against the jostling of the flights, which feel remarkably bumpy at the back of the plane. During the gaggle, reporters clutch seat backs, the wall, even one another to stay upright. And more than a few gaggles have lasted all the way through landing.

“Hang on, guys,” Carney exclaimed on a recent trip to Virginia Beach after noticing the runway through the window.

“Okay, no one has fallen,” Psaki added as the airplane landed.

Perhaps that informality has emboldened Psaki to showcase her personality. But it hasn’t always come out the way she’d hoped. During one gaggle — this one on the ground in Nevada, where Obama was preparing for his first debate — she was asked what else the president was doing with his time. Her answer landed with a thud:

“Well, I know this may surprise you. I’m not spending time with him in his room at 11 p.m.”

The goal of the joint gaggle, spelled out by the White House as a legal precaution, is to show that the administration is focused on the business of governing — and that the campaign is a separate enterprise. It’s not an unprecedented setup: Bill Clinton installed a campaign spokesman, Joe Lockhart, alongside his official press secretary, Mike McCurry, in 1996. George W. Bush did the same eight years ago, when campaign representatives Nicolle Wallace or Scott Stanzel shared the aisle with White House press secretary Scott McClellan.

Nonetheless, the “clear lines of distinction” seem less clear this time around. Wallace recalls holding her campaign press availabilities on the ground, not on Air Force One, for the sake of appearances. She can’t recall McClellan ever commenting on a John Kerry ad — something Carney does occasionally “as a matter of policy.” On one such occasion, Carney defended his remarks about an ad accusing Obama of rolling back welfare reform: “It is absolutely incumbent upon me, as the president’s spokesman on matters of policy, to push back against blatant falsehoods like that.”

There’s no legal requirement to separate the functions of the campaign from the White House. Unlike independent committees, which are forbidden to coordinate with the candidate they support, advisers at campaign headquarters in Chicago talk daily to the White House brain trust to be sure that everyone is in sync.

Listen closely, and it’s clear that Carney and Psaki are often saying the same thing.