Faced with a recalcitrant Congress and a constrained budget, President Obama and his top aides are increasingly working to mobilize an outside coalition of corporate, nonprofit and academic groups to promote White House economic and social policies.

The strategy will be on display Thursday as the White House holds a summit with more than 100 college and university presidents, who will promise to enroll more low-income students and ensure that they graduate. This month, the administration also will sponsor a session for corporations that pledge to hire the long-term unemployed.

The president is privately exhorting his allies to do more on a range of other issues as well, including foreign investment in the United States, youth and women’s issues, and the hiring of military veterans.

It’s a simple strategy with a bureaucratic name: using the president’s “convening authority” to bring together the private and nonprofit sectors to move ahead on his agenda when Congress won’t, and then showcasing this action through traditional and social media.

“I’ve got a phone that allows me to convene Americans from every walk of life — nonprofits, businesses, the private sector, universities — to try to bring more and more Americans together around what I think is a unifying theme: making sure that this is a country where if you work hard, you can make it,” Obama said Tuesday before meeting with members of his Cabinet.

But White House officials acknowledge that the approach has its limits and is no substitute for major legislation to rebuild the nation’s infrastructure or overhaul immigration laws. Some groups the White House has approached say the initiatives in their areas have not had major policy consequences.

And on some issues, such as early childhood education, any real policy changes are unlikely to happen until after Obama leaves office, officials said.

Chris Caine, president and chief executive of the D.C.-based consulting firm Mercator XXI, who has worked on similar initiatives with Democratic and Republican administrations, called it a “20-80 proposition.”

“Twenty percent of the time something’s going to happen, which has meaningful impacts on the economy and American life,” he said. “Eighty percent of the time these convening sessions are initiatives run out of the integration of the White House policy and political shops and end up being a mere daily sound bite. After all, we have a 365-day electoral calendar that never stops.”

National Economic Council Director Gene B. Sperling, who has spearheaded the upcoming college and skills summits, said the White House expects concrete commitments from every attendee, in the same way that foundations such as the Clinton Global Initiative require pledges from participants.

“Whenever I spoke to any group of college presidents, foundations or businesses, we made crystal clear that we are not doing a conference to do panels for panels’ sake or to talk about what everyone thinks they are already doing good,” Sperling said. “We made clear we are doing this to change the world by changing the paths of young people’s lives.”

Presidential senior adviser Dan Pfeiffer said in an interview that when Obama reaches out to the leaders of businesses, schools and nonprofit groups, “that’s using the power of the presidency and the Oval Office to urge people to do things. And that’s a significant thing.”

The practice of convening outside groups to promote the president’s agenda dates as far back as Theodore Roosevelt, who held White House conferences touting the importance of conservation and other matters. Ronald Reagan used a public-private approach to update workplace safety reporting methods; George W. Bush establish the Energy Star efficiency program through the same process; and Bill Clinton invoked it to create voluntary standards for electronic commerce.

Many nonprofits like the partnership approach because it allows them to raise more money and experiment. For example, a group of corporations, foundations and educational institutions have begun “100K in 10,” aimed at hiring 100,000 science, technology, engineering and math teachers by 2021 after Congress did not act on a similar proposal by Obama.

Other groups have taken advantage of the Social Innovation Fund, a program that started in 2009 and allows nonprofits to match federal grants and then give to other philanthropies that match the money as well.

Matthew Klein, executive director of Blue Ridge Foundation New York, which has shared $25 million over five years from the fund to promote college access for low-income youths and other causes, said it’s a way to help nonprofits “leverage their work and help them do better.”

“I don’t think anyone’s saying, ‘We’re in a tough political climate, so private philanthropy and nonprofits should take over what is necessary for social impact,’ ” Klein said, adding that his group has been able to experiment and raise money from other donors “because of the imprimatur of the White House and our association.”

One of the key areas for private-sector participation is education. White House aides became intrigued by a growing body of academic research showing that low-cost interventions, such as mailing a packet of scholarship information, made it far more likely that disadvantaged students would be admitted to a selective school.

Christopher Avery, a public policy professor at the Harvard Kennedy School who has consulted with Sperling on Thursday’s summit, said the current system “screens people out if they haven’t already gone through the process. . . . I always thought education was supposed to be the engine of addressing income inequality and social mobility.”

The conference will feature leaders such as Franklin & Marshall College President Daniel R. Porterfield, whose school has nearly doubled its financial aid to first-year students over the past five years and more than tripled the number of incoming students who are eligible for Pell grants during that period.

Porterfield, who met with Sperling along with a handful of other college leaders on Nov. 13 to help develop policy targets for the summit, said he has held meetings on his campus asking how the school’s level of ambition can be raised even higher.

“When the White House rings the bell, all of us go to the starting line ready to intensify our work,” he said in an interview. “We’re asking ourselves, ‘What more can we do?’ ”

But some academic officials are skeptical.

“A number of colleges and universities are making a concerted effort to expand their outreach and improve the affordability and accessibility of a college education, and events like this are unlikely to have a significant impact, either positive or negative, on those efforts,” said one official from a school participating in the event, who spoke on the condition of anonymity to be frank.

Other initiatives have called on companies to recruit more military veterans and young people, who were among those hit hardest by the economic downturn. The Joining Forces initiative, championed by first lady Michelle Obama, obtained commitments from companies to hire 380,000 veterans or their spouses by the end of 2013.

After Obama’s $1.5 billion proposal to provide jobs for low-income youths ages 16 to 24 did not gain traction in Congress, the White House secured pledges from firms to provide 180,000 summer youth jobs in 2012. PricewaterhouseCoopers hired 1,500 young people that year, and a similar number in 2013; CVS Caremark agreed to hire more than 20,000 part- and full-time young employees.

It is unclear exactly how many of these firms altered their hiring practices as a result of the Summer Jobs+ program, however. A spokeswoman for CVS Caremark said the company provided about the same number of summer jobs over the past three years.

But Pfeiffer said just focusing on such issues — such as the benefits of hiring people who have been unemployed for several years — can shift public attitudes.

“Does that mean we can get enough companies to solve the long-term unemployment problem? Absolutely not,” he said. “But every person you hire, you’re giving people an opportunity they don’t otherwise have, and that’s a great thing. Sometimes there’s a tremendous micro-benefit, and a macro-benefit.”