NEW YORK – Facebook’s Sheryl Sandberg recently threw a fundraiser for President Obama, dining with Lady Gaga and the president himself.

Last month, Sandberg was a highly visible co-chairwoman of the World Economic Forum in Davos, Switzerland.

As Facebook prepares to raise $5 billion in an initial public offering outlined last week, Sandberg, the company’s chief operating officer, is about to be thrust even further into the limelight.

Since joining the company in 2008, she’s become the public face of the social media giant, forging ties with advertisers, policymakers and partners. With the IPO, heralded by a regulatory filing last week, Sandberg will be taking on a larger function helping senior management represent the company to a broadening investor base and to Wall Street analysts.

“She’s going to play a crucial role in everything that happens over the next few months,” said Matt Cohler, a special adviser to Facebook and general partner at Benchmark Capital in Menlo Park, Calif. “She is very deeply connected” in political and business circles, said Cohler, who served as a Facebook vice president from 2005 to 2008.

At 42, Sandberg serves as the outgoing and more seasoned foil to Chief Executive Officer Mark Zuckerberg, a 27-year-old coder who sets the company’s strategy even as he shuns publicity. During a career that has spanned Google Inc., McKinsey & Co. and the U.S. Treasury Department, Sandberg has honed what friends, colleagues and former employees say is a penchant for brokering alliances, fostering loyalty and setting priorities.

“She brings an enormous amount of credibility and experience,” said Anupam Palit, research head at GreenCrest Capital in New York. “She knows how a public technology company works, she knows what investors are looking for with these types of companies, and, more importantly, she knows how to successfully deliver against those expectations.”

Sandberg declined to comment for this story.

Her role as Facebook’s ambassador in chief was in full display last month at Davos, where she was one of six co-chairs of the forum. She participated in such panels as “Women as the Way Forward” and collected business cards from attendees who stood in long lines for a moment of her time.

As Zuckerberg focuses on the technology that has helped Facebook amass more than 800 million users, Sandberg has trained her attention on the advertisers whose aim to reach social-media consumers propelled sales to an estimated $4 billion in sales in 2011.

She traveled to Bentonville, Ark., on two occasions last year to persuade Wal-Mart Stores Inc. to devote more of its ad budget to social media. Thousands of employees showed up on a Saturday to hear Sandberg talk about interacting with customers through the social network.

“She was wise to commit as much as she did to that because it helped me internally to get people on board with a lot of the programs we are doing with Facebook,” Wal-Mart Chief Marketing Officer Stephen Quinn said in an interview. “Our best partners have made the trek to Bentonville. It is unusual to do it several times a year.”

Sandberg, who has played a key role in boosting Facebook’s staff to more than 3,000 employees, also spends much of her time grooming top deputies, according to people who work with her.

The list includes advertising head David Fischer; human resources head Lori Goler; vice president of partnerships Dan Rose; and Elliot Schrage, vice president of global communications, marketing and public policy.

“What makes her unique, even in her peer group, is that she is deeply committed to investing in people,” said Bryan Schreier, a venture capitalist at Sequoia Capital who previously worked under Sandberg at Google.

“When she’s investing in you, it feels like she only has time to do that for one person, but she can actually do that for dozens.”

Sandberg grew up in a middle-class Miami suburb, then studied economics at Harvard University. There she met Larry Summers, with whom she later worked at the World Bank and the Treasury Department.

Sandberg spent seven years at Google, where she eventually ran global ad sales. Her experience with Google’s stock-market debut, in 2004, will help prepare for the offering at Facebook, said Lise Buyer, an IPO consultant who worked on the Google deal.

“Having observed what Google did right about educating employees on the wide variety of topics associated with an IPO would certainly be really helpful,” said Buyer, who now runs the Class V Group in Portola Valley, Calif. “Equally, having observed some of the nuanced errors where Google did not get it right will also be very helpful.”