Relaxed and chatty, Ann Romney passes out homemade Welsh Cakes, her grandmother's recipe, aboard the campaign plane bound for Tampa. (Melina Mara/THE WASHINGTON POST)

The White House press corps got off the bus. At a fairground here, the group followed a young woman in waxy red lipstick who held a sign that said, “Drop Gear Here.” As law enforcement officers “swept” the “dirty” media types “clean” with mag wands, television reporters killed time by using the hindquarters of a giant plaster cow as the backdrop for their playful iPhone camera reports. A woman from the White House travel staff held a sign that said, “Follow Me,” while another yelled, “To the right! To the right! To the right!” The reporters trudged, cattlelike, to a media file center.

In the front of the room, a heavy blue curtain, along with a lectern flanked by an American flag and an Iowa state flag, provided a presidential backdrop for news conferences. The same tableau appeared in every state, with only the colors of the state flags changing from Florida to Ohio to Colorado. It never served as more than a media tent decoration.

In many ways, little has changed for traveling reporters since the old days, most famously documented in Timothy Crouse’s 1973 classic book “The Boys on the Bus.” In both Mitt Romney’s and President Obama’s press corps, there are still all the indignities of pre-dawn wake-up calls and hours of travel to hear the same speeches in different locations. There is still the dependence on pool reports, the dangers of groupthink and the temptations of Stockholm clubbiness (Flag football with the Romney staffers on the beach, anyone? Mitt’s flipping the coin!). There is drinking (less now) and eating (more now), and tensions still surface among reporters (a shouting match over journalistic ethics broke out on the Obama plane). The boredom on the Romney trail has produced photo albums’ worth of gauzy, self-documenting Instagrams.

In fundamental ways, though, nothing is the same. And not just since 1973, but since the last presidential election. Despite the usual complaints of lack of access to candidates — practically speaking, there isn’t any — the power dynamics between the campaigns and the media have shifted significantly toward reporters. And the old journalistic hierarchy that once aggrandized major newspapers and national networks has flattened out, giving any boy, girl or baby on the bus with a Twitter feed the same opportunity to drive the race as the most established brand names.

In a political-media industrial complex built on conflict, this is a rare point upon which the opposing campaigns and reporters all agree.

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“Once we got to the Internet/cable-news cycle, really in 2004, there was no capacity to control” the message, said Dan Pfeiffer, the White House communications director. “I leave it to others to judge if the power has gone from us to the reporters. I don’t know that, and it probably depends on the day, but among the community of reporters, the difference between the A-Number One political reporter and the embed-off-camera producer, that distance has shrunk dramatically.”

That is just fine for the new wave of reporters and the zero-to-60 Web publications to which they belong. “It’s more competitive,” said McKay Coppins, a young reporter for BuzzFeed, an outlet that prides itself on knowing what people want to read and share on social media.

Until January, when it hired the reporter and blogging pioneer Ben Smith as its editor in chief from Politico — the belle of the past cycle’s ball — practically no one in politics had heard of BuzzFeed. Now, its reporters are on the Obama and Romney campaign buses, receiving respect and attention from the most senior campaign officials. “If you are some old-school newswire reporter who, along with six other guys, used to write the entire election narrative, it stinks,” Coppins said. “But it’s a great time to be a young reporter.”

Presumptuous? Maybe. The New York Times as an institution, and some of the gold-plated names of political journalism — such as The Washington Post’s Dan Balz, the National Journal’s Ron Brownstein — still shape big-picture conventional wisdom. And to the extent that there are still a few reporters on the planes with experience covering previous presidential races and sifting through spin, that perspective can’t hurt.

But Coppins is expressing what everyone in politics already knows: that Twitter is the local bugle of every reporter and operative, and that a scoop or unique observation or compelling story effectively promoted on Twitter, and picked up by arbiters with massive numbers of followers, can drive the conversation more than almost anything else. This development is good for smart, industrious reporters of any age, less good for hacks hoping to rest on their laurels or coast on whatever remains of presidential press-corps prestige, and straight-up bad for campaigns in the business of controlling a message.

“There is a change in the relationship,” Pfeiffer said. “There is a tension with the press being on 24-hour gaffe control and their demand for interaction and access.” He added, “Everything in a campaign you judge on a ­risk-benefit analysis, and the nature of the media has dramatically increased the risk while the benefit has stayed the same.”

And that risk now extends far beyond the plane.

“The access to the technology has made it so that what happens on the plane is basically served up and consumed by everyone outside it instantly,” said Kevin Madden, a Romney adviser who was the candidate’s press secretary in 2008.

“It’s a lot like everybody is on the plane,” he said.

The result of all this is a press corps that shadows, but rarely interacts, with the candidates or the campaigns. Jen Psaki, the traveling spokeswoman for the Obama campaign, doesn’t actually travel with the reporters in the White House press corps. She rides with Obama and other advisers on Air Force One. (A pool reporter on the president’s plane keeps colleagues in the loop.) That the campaign suddenly plopped Pfeiffer and senior adviser David Plouffe on the press bus and plane during a recent dash through swing states made the contrast only sharper.

The Romney press corps is no more accustomed to meaningful interaction. In a recent swing through Ohio, Richard Gorka, the traveling press secretary, rode with the Romney campaign staff and not on the media bus trailing it. On the plane, Stu Stevens, Romney’s senior strategist, drifted with cupcakes to the back section, where the reporters are corralled, and then disappeared to the first-class cabin with Romney.

On the surface, this may seem like the campaign exercising total control. In fact, it is a total relinquishing of control. Reporters for both new and more established publications used the same word to describe the nearly entire lack of access or information or even standard comment from the campaigns: “freeing.”

“Because they don’t comment, you are freer,” said one reporter who works for a prominent publication and was traveling with Romney and not authorized to speak on the record. “They have no leverage, and so you’re freer to write harder stories.”

Whether the press corps has made the most of that freedom is a fair question and will certainly be fodder for media critics after Election Day. But what is clear is that the best the campaigns can do is react — react to the stories reporters write, react to the TV segments reporters produce and, most of all, react to the instant analysis and potentially viral observations reporters post on Twitter. And this, more than anything, is where everyone’s energies have gone.

“Toby, I’ll have you know, tweeted out that in 2009, a Welsh guard won a military cross for bayonetting Taliban,” Stevens, the Romney senior strategist, told a bunch of reporters in the spin room after the final presidential debate, in Boca Raton, Fla., where Obama sarcastically suggested that Romney’s understanding of the military is as outdated as the use of bayonets and horses. Toby Harnden, the U.S. editor of the Daily Mail in London, corrected Stevens, noting that the tweet referred to the Royal Regiment of Scotland.

“Isn’t that great?” said Stevens, smiling and squinting. “It’s my favorite tweet of the campaign.”

Stevens spent a good portion of the final debate — and the entire campaign, for that matter — sending e-mails expressing pleasure or displeasure with what reporters tweeted. Reporters — some of whom have tens of thousands or hundreds of thousands of Twitter followers — said it was clear that both camps assigned staff members to monitor and flag their tweets.

Jake Tapper, an ABC News reporter who has more than 200,000 Twitter followers — a tiny fraction of the audience that watches his dispatches on “World News Tonight” — said that “based on the reaction from the Obama or Romney campaigns, you wouldn’t know that the tweet reached a tenth, a twentieth, a fiftieth of that audience.”

Coppins and others also have taken notice.

“In a way, it’s beyond that they don’t have control over what outlets write — they are grasping for control over individuals and what we tweet,” Coppins said. “If I write, ‘Man this crowd is really lame,’ I just wrote the narrative.”

The Romney and Obama campaigns acknowledged keeping a close eye on Twitter because, as inside baseball as it may seem to the uninitiated, it had the power to shape the thinking that made it to the front page of the New York Times or the evening news, which then trickled down to local swing-state media that could sway voters.

“If there seems to be a Twitter consensus — and when I say consensus, I mean two or three people have an evaluation of a speech — it can drive things,” said a senior Obama adviser. “But you find that in the day-to-day coverage, it’s hard to figure out who is the one person. There just seems to be a movement in a direction.”

And the direction is away from the campaigns.