President Barack Obama and guests gather for a Super Bowl party at the White House. “You need to be there all the time,” photographer Pete Souza says of his White House position, which he also held for five years during Ronald Reagan’s presidency.

Photographer Pete Souza was there as the president got a helping hand from Vermont Gov. Jim Douglas.

An Oval Office shot by Pete Souza is one of the countless images he produces daily. Five hundred photos in one day? That’s a light day.

White House photographer Pete Souza especially likes an inauguration night image of the president nuzzling first lady Michelle Obama in a freight elevator while Secret Service agents awkwardly try to avert their eyes.

Washington, D.C ? No time to check lighting. Forget about fiddling with the lens, lining up the composition.

Reflexes take over.

Point. Click.

Nailed it.

The photographic image snared by Pete Souza tickles the synapses, a behind-the-scenes moment of the most delightful and surprising kind. There is President Obama — the leader of the bloomin’ free world, for goodness’ sake — moving the sofa back into place after a routine photo op in the Oval Office!

Doesn’t the prez have people to do that sort of thing? Don’t his people have people who have people who could have handled that little chore?

Even Souza — an “old warhorse” of political photography, as former Time photographer Dirck Halstead describes him — can’t believe it.

“I was not expecting that,” says Souza, who became the Obama White House’s official photographer in January, two decades after handling those duties for another photogenic Oval Office occupant, Ronald Reagan. “The president of the United States doesn’t move furniture back in place!”

Ah, but he does. Souza’s picture tells us so.

Souza, who holds a master’s degree in journalism and mass communication from Kansas State University, is the photographer who gets to stay in the room when all the other photogs are shooed away — when just about everyone is shooed away. In the pressurized atmosphere of the presidential bubble, Souza gets to disappear into the molecules, viewing moments the rest of us could only dream of seeing.

“I don’t know if ‘fly on the wall’ is too much of a cliche,” says Souza, a 54-year-old with dark eyes, a prominent nose and thick features.

So, on inauguration night, Obama shows off his party tux in a White House hallway for the first kids, Sasha and Malia. Souza’s there.

Click.

The president nuzzles the first lady in a service elevator between inauguration balls.

Click.

POTUS gives the touchdown sign while watching the Super Bowl in the White House.

Click.

Slouching in the Oval.

Click. Click. Click.

The momentous and the numbingly dull. It’s all there in Souza’s eye, all there in his Canon 5D Mark II camera. Five hundred photos in one day? That’s a light day. Sometimes, it’s 1,000 or 1,500, so many photos that Souza can only guess at the exact tallies.

How many different ways can you photograph the same man talking on the same phone? Souza knows. He shoots nearly all phone calls the president makes to other world leaders, just in case one of those calls is (begin ital) the (end ital) call. A moment that shapes history.

“You need to be there,” Souza says, “all the time.”

White House history

As long as there have been cameras, we have craved images of our leaders. James K. Polk in the late 1840s was the first president to be photographed in office, according to the White House. (Others have asserted that William Henry Harrison was first.) The famed Civil War photographer Mathew Brady preserved every deepening furrow of Abraham Lincoln’s face. And Teddy Roosevelt is often called the first president to be photographed “in action,” allowing guys with cameras to trail him while he worked.

But it wasn’t until the 1960s that the White House formalized the rite of presidential photography. Cecil Stoughton, an officer in the Army Signal Corps, became the White House photographer during the administration of John F. Kennedy. His images commingled with photographs taken by several others to create Kennedy’s Camelot mystique.

But Stoughton’s most famous photograph — perhaps the most enduring image captured by an official White House photographer — is the cramped, harrowing scene of Lyndon Baines Johnson taking the oath of office aboard Air Force One, a shattered Jackie Kennedy at his side, on the day of Kennedy’s assassination. Historians credit the photograph with conveying a sense of reassurance and continuity to a startled nation. If there’d been any doubt about having an official White House photographer, it surely ended that day.

Official White House photographers are not journalists. They work for the president, and the White House press office decides which of their images will be released to the public. It follows that there would be a temptation to lean toward distributing photos that show the president in the best light. Eventually, though, all the photographs make their way to the National Archives and to presidential libraries.

Souza considers himself a documentarian, a collector of moments that will form the historical record. In “Images of Greatness,” Souza’s compilation of photos from more than five years as an official photographer in the Reagan White House, he describes himself as one of the president’s “shadows.”

Souza, who also served as the official photographer for Reagan’s funeral, writes that his “personal political philosophies didn’t necessarily mesh with Reagan’s” but that he was “glad fate and good luck put me inside his White House.” Souza didn’t respond to a question about whether his political views align with Obama’s.

Souza’s Reagan is at once magisterial — bathed in warm, almost cinematic light — and playful. Here is Reagan tapping golf balls on Air Force One, slipping into a Michael Dukakis mask, tossing a paper airplane off a hotel balcony in Los Angeles. (The White House didn’t much like that airplane shot, refusing to release it until Reagan’s last month in office, Souza writes. He later framed the photograph for Reagan, signing it “Mr. President, bombs away.”)

Souza says he usually is too busy worrying about getting his shot to listen to his subjects. But he writes of hearing a snippet of unforgettable conversation at a stalled nuclear summit between Reagan and Soviet leader Mikhail Gorbachev in Reykjavik, Iceland, in 1986. Gorbachev said: “I don’t know what else I could have done.” Reagan responded: “You could have said, ‘Yes.’ “

Souza told presidential aide Pat Buchanan what he’d heard, Souza writes, and Buchanan “barked: Write it down! Write it down!” White House press secretary Larry Speakes released the conversation “verbatim from my notebook to Time magazine,” Souza writes.

Souza’s photographs from that day show Reagan with pursed lips, anger and weariness etched on his face. They contrast with the cheery Gipper of our memories, the horseback-riding optimist.

But it was not those iconic Reagan images, it seems, that really got Barack Obama’s attention.

It was a picture of a little girl.

‘Round the clock duty

In 2004, Souza was working in Washington as a photographer for the Chicago Tribune. A colleague, Jeff Zeleny — now a political writer for The New York Times — asked him to take photographs for an ambitious project documenting Obama’s first year as senator.

Souza hadn’t seen the now-legendary speech at the Democratic National Convention that launched Obama. But he quickly figured out that “there was just something special about this guy that I hadn’t seen in a lot of other politicians,” he says one recent morning in his snug West Wing office, which once served as a barbershop.

On the day Obama was inaugurated as Illinois’ junior U.S. senator, Souza captured an image of him squatting to talk with his daughter Malia, then 6. The shot exudes warmth, an intimate family moment. Another photograph shows his younger daughter, Sasha, hamming it up during the swearing-in ceremony. Days later, Souza says, Obama picked him out of a crowd and complimented him.

The marquee shot from Souza’s journalistic coverage of Obama may be one that shows him bounding up the stairs of the Capitol. Obama, seen from behind, is in motion, a kinetic metaphor of the young, vibrant politician in his ascendance.

“It doesn’t get any better than that image,” says Bill Luster, a photographer at the Louisville Courier-Journal who has befriended Souza on frequent trips to Washington. “It’s a simple picture. His pictures are very simple in terms of composition. At the same time, they are complex in terms of content.”

Time and distance, though, elevate other photos in Souza’s Obama portfolio, which have been compiled for a book published last summer: “The Rise of Barack Obama.”

In one, Obama sits with his feet on the desk in a sparse, temporary office he occupied after entering the Senate — nothing about the image hints that this man is soon to become among the most recognizable human beings on Earth. In another, Obama walks unrecognized on a Moscow street. It is one of Souza’s favorites.

“This is a picture,” Souza says, “that is never going to be taken again.”

When the White House called, Souza had left day-to-day picture taking for a job teaching photojournalism at Ohio University. Before saying yes, he says, he wanted to make sure that he and Obama agreed that his focus would be documenting the presidency for history’s sake. It is a goal, Souza says, that Obama buys into.

“I was a little surprised. A lot of people were surprised,” Souza’s friend, Halstead, says of his decision. “Pete was working in the private sector for so long that he may have forgotten how difficult it is … you have to be available around the clock.”

You also become a public figure. When Obama addressed Congress on Tuesday night, there was Souza over his right shoulder, clicking away. Because of the Internet, Souza may have a wider audience for his photos than any White House photographer in history. The White House Web site has been revamped from the Bush days and now features a huge rotating display of photos by Souza and the other photographers on his staff, giving them a tremendously high-profile forum for their work.

You are part of historic moments great and small. A small first: Souza’s official presidential portrait of Obama is the first to be taken with a digital camera.

Souza is an exceedingly popular and respected figure in Washington’s tight-knit photography circles. Friends say he is an inveterate practical joker and generous colleague.

But he is clearly ill at ease with his fame, insisting that interviews be confined to discussions of his photographs, rather than his personality or personal life. During a brief interview one recent morning, Souza is flipping through photographs.

He especially likes an inauguration night image of the president nuzzling first lady Michelle Obama in a freight elevator while Secret Service agents awkwardly try to avert their eyes. Obama has draped his tuxedo jacket over her shoulders, and they are looking deeply into each other’s eyes. No other photograph hangs on Souza’s office wall — the image reflects in the old barbershop mirror behind his desk.

“It tells a complete story,” Souza says of the photograph. “You know exactly what’s going on.”

There are more photos on the desk, more moments for reminiscing. But Souza’s eyes keep wandering to the clock.

He rises and makes his apologies. He’s got to go, Souza says. The president is about to make a phone call.