On the sidelines of an international summit, the Democratic incumbent attempted to dismantle his Republican rival’s business pedigree while declaring it an insufficient rationale to lead the nation. In so doing, Obama left no doubt that Romney’s business background as founder of Bain Capital, perceived by many as a political strength during a weak economy, would be a recurrent target of his campaign.

Romney responded swiftly, saying Obama was attacking the free-enterprise system. He made it clear that the issue would remain a point of contention for the remainder of the race.

Obama made the comments in response to a question about Newark, N.J., Mayor Cory Booker’s weekend criticism of the Obama campaign’s attack on Romney’s private equity background. Booker, an Obama supporter, called exchanges by the campaigns over Bain “nauseating” and a distraction from issues that interest voters.

“This is not a distraction,” Obama said pointedly at a news conference filled with international media that marked the end of a NATO gathering. “This is what this campaign is going to be about.”

Obama argued that the priority of private equity enterprises such as Bain’s is “to maximize profits.”

“And that’s not always going to be good for communities or businesses or workers,” he said.

Obama’s comments came as his campaign has been doubling down on Romney’s tenure at Bain, a private equity firm he helped found in 1984. In ads and in Web videos, the campaign has drawn attention to companies that Bain took over only to close them or let them fail, costing jobs and hurting communities. Obama also has dispatched Vice President Joe Biden to battleground states — and specifically economically struggling areas filled with white blue-collar voters — to assail Romney on the matter.

Asked about Booker’s remarks Monday, Obama praised the mayor but left no doubt that the line of attack would be central to his re-election effort.

The president was careful not to criticize private equity or profit making in general. But by standing by the Bain criticism, Obama also risked feeding a story line that he is anti-business and eager to restrain and tax the private sector in pursuit of his vision of fairness.

The line of attack illustrates Obama’s complicated relationship with the business community. He has used populist language to attack Wall Street executive and bankers as “fat cats,” and called for an end to tax subsidies of oil and gas companies, but he also expanded the government’s rescue of the auto industry and has promoted tax breaks for small businesses.

While some of his Wall Street support has waned, he still draws a significant amount of campaign contributions from major investors, retaining a good relationship with, among others, billionaire investor Warren Buffett.

At the news conference, Obama acknowledged that businesses that seek to turn a profit by investing in struggling companies often succeed in creating new jobs and new industries — an argument Romney himself has made in pointing to his accomplishments at Bain.

“When you’re president, as opposed to the head of a private equity firm,” he added, “then your job is not simply to maximize profits. Your job is to figure out how everybody in the country has a fair shot.”

Romney’s campaign has welcomed the election-year debate on jobs, arguing that the former Massachusetts governor generated tens of thousands of jobs in the public and private sector.

“President Obama confirmed today that he will continue his attacks on the free enterprise system, which Mayor Booker and other leading Democrats have spoken out against,” Romney said in response. “What this election is about is the 23 million Americans who are still struggling to find work and the millions who have lost their homes and have fallen into poverty. President Obama refuses to accept moral responsibility for his failed policies. My campaign is offering a positive agenda to help America get back to work.”

Obama’s attack underscores his campaign’s recognition that the economy trumps all other issues.

While the economy has begun to recover under his presidency, the turnabout has been slow and marked by high unemployment that remains above 8 percent. For Obama, his challenge is persuading voters to stick with him as he tries to help the economy rebound while withstanding criticism from Romney that the president’s policies have hindered the recovery.

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Kuhnhenn reported from Washington. Associated Press writer Ken Thomas in Washington contributed to this report.

“No pictures!” shouted one Marine. Another warned: “If I see a cell phone used to take a picture, it will be confiscated.”

Photographers are tightly monitored, with Marines determining the timing and the angle of their shots. As photographers awaited the “family photo” of G-8 leaders Saturday morning, photographers had to cap their lenses and television crews had to place small white hoodies over the front of their cameras.

Once given the go-ahead, lenses rose in near unison and shutters clicked and whirred. Then, silence as the press waited for President Barack Obama and the rest of the G-8 membership to show up.

The orders from the Marines were equally clear for the end of the photo ceremony: “When leaders are out of sight, the lens caps go back on.”

Even Obama got in the act. As the press was ushered into Laurel Lodge for a brief statement before a working session, Obama told the media contingent: “The press, you’re welcome as long as you don’t break anything.”

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Forget the situation in Iran, Syria or the eurozone. The most menacing problem at Camp David may be the swarming gnats.

Shortly before the official G-8 photograph near Aspen cabin, the president’s lodge, two blue-shirted military stewards sprayed an anti-bug fog down the path that the leaders took to the platform for the photo. The stewards repeatedly sprayed the area around the photo platform to keep gnats at bay.

“I hear the gnats have been getting you guys, huh?” Obama asked as reporters tried in vain to shoo away the tiny flies.

During the photo, the G-8 leaders managed to avoid being caught for history, hands busily swatting away insects.

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Obama has rolled out the red carpet for new French President Francois Hollande, greeting him at the Oval Office and spending time with him at Camp David.

So Hollande is trying to repay the courtesy.

When reporters asked Obama for a word in French, the U.S. president turned to Hollande and declared, “he’s my translator!” He told Hollande to “tell them I say, ‘Welcome.’”

Hollande obliged, saying in French, “He says, ‘welcome’ to you.”

Facing economic and political pressures at home, President Barack Obama and leaders of Germany, France, Canada, Italy, Great Britain, Russia, and Japan were huddling in the casual setting of Camp David’s Laurel Lodge looking to build consensus even though a decisive plan of action seemed out of reach at this point.

The G-8 session here in this secure presidential compound nestled in Maryland’s Catoctin Mountains sets the stage for a far more consequential European summit next week where eurozone members hope to come together on specific steps to fight rising debt while spurring a recovery.

Obama established the tone for the G-8 Friday after meeting with just-elected French President Francois Hollande, declaring that the aim of the summit is to promote both fiscal consolidation and a “strong growth agenda.”

“President Hollande and I agree that this is an issue of extraordinary importance not only to the people of Europe but also to the world economy,” Obama told reporters following the meeting.

In a hint of the pressures facing the leaders, Obama greeted German Chancellor Angela Merkel to Camp David Friday at dusk, asking her how she was. Merkel, facing resistance over her austerity push, merely shrugged.

“Well, you have a few things on your mind,” Obama said sympathetically.

A central economic topic, though hardly the only one confronting Europe, is the fate of Greece which is facing the most acute financial crisis of the eurozone and is set to hold elections June 17 to end political deadlock. At issue is whether Greece abandons the euro to escape austerity measures.

Hollande, speaking with Obama at his side Friday, said: “We share the same views, the fact that Greece must stay in the eurozone and that all of us must do what we can to that effect.”

Lowering expectations for the G-8, U.S. National Security Adviser Tom Donilon said: “The leaders I think will focus on specifics and specific concepts and ideas for growth and jobs. But I would also point out that the ultimate decisions on that would be decisions taken in the eurozone.”

Also on the agenda is energy as the world looks to the oil markets in advance of scheduled sanctions on Iranian oil exports. While oil prices have been falling, major oil importing countries, including the U.S., are keeping a wary eye on prices and keeping open the possibility of tapping their own oil reserves.

For Obama, Europe’s fate is critical to his own political survival. An economic recession that spreads to the U.S. could damage an already slow recovery and boost the argument by his Republican challenger, Mitt Romney, that the United States economy needs new leadership.

There is a get-acquainted aspect to the session as well. The Camp David gathering, the largest collection of foreign leaders ever at the presidential retreat, is the first G-8 meeting for Hollande, for Italian Prime Minister Mario Monti and for Japanese Prime Minister Yoshihiko Noda. In what has been widely viewed as a snub, Russian President Vladimir Putin is skipping the G-8, sending Prime Minister Dmitry Medvedev in his place.

The meeting comes at a turning point in Europe, marked by elections in France and Greece that signaled defiance toward the fiscal austerity measures that Merkel has pushed for the most indebted eurozone countries. European countries are straining under high borrowing rates. The drastic cuts in spending and government layoffs were designed to address massive national debts but they have also caused short-term economic distress and joblessness.

On Friday, Spain’s central bank announced that the level of bad loans on the books of Spanish banks was at an 18-year high, fueling concerns about the financial sector in the eurozone’s fourth-largest economy.

The emphasis on economic growth has been welcomed by Obama, who has long argued that the stimulative steps he took in 2009 put the U.S. on the road to recovery.

“Europe is still in a difficult state,” Obama told donors in Seattle last week, “partly because they didn’t take some of the decisive steps that we took early on in this recession.”

To what degree the Europeans, and Merkel in particular, agree remains to be seen.

“With Hollande coming into play here, there is going to be a lot of pressure on Germany, not just from Hollande and Obama, but also some of the other countries — Italy and UK — some pressure for Germany to push more toward growth within Europe because they have to get them on board,” said Jeffrey Bergstrand, a former federal reserve economist and now an expert on international finance at the University of Notre Dame.

U.S. officials have been encouraged by recent discussions in Europe to ease up some belt-tightening so that spending cuts aren’t as deep or as swift and to increase spending on public works projects like roads and schools in weaker parts of Europe. They also point to Germany’s recent decision to negotiate higher public sector wages, a move they say could have a positive ripple effect on demand.

Merkel herself has made conciliatory gestures, saying in a television interview this week that she was open to helping stimulate the Greek economy provided Greece honored pledges to shrink its debt.

To Russian Prime Minister Dmitry Medvedev, in a bright blue jacket: “Dmitry, good to see you my friend, How are you?”

Medvedev: “Fine, Barack, not so bad.”

Medvedev nodded at Laurel lodge and joked: “This is my new place.”

To German Chancellor Angela Merkel: “Angela! … How have you been?”

Merkel, faced with rebellions in Europe over austerity measures she has pushed, shrugged.

Obama: “Well, you have a few things on your mind.”

All the guests but new French President Francois Hollande dressed casually, with open collars and blazers.

“Francois, we said you could take off the tie,” Obama said, ribbing him.

Hollande smiled with a look of protest: “For my press…”

Obama responded: “For your press, you must look good.”