WASHINGTON — The Barack Obama Foundation added three board members on Thursday, all big donors, as President Barack Obama and first lady Michelle face the daunting challenge of raising hundreds of millions of dollars to construct and endow their museum and library.

The new board members are Michael Sacks, John Rogers Jr. and Robert Wolf, all with close ties to Obama.

Sacks and Rogers, who are enormously active in a variety of Chicago philanthropic and nonprofit organizations, also will help figure out how the Obama Center, to be constructed on the South Side, will fit into the civic fabric of Chicago.

The board of the foundation, with headquarters in Hyde Park, expands to 10 as the Obamas’ are stepping up their post-presidential planning in the final months of Obama’s second term.

On Wednesday, during a question-and-answer session with kids whose folks work in the White House, Michelle Obama was asked how she was going to keep Let’s Move! and her other initiatives going.

“We’re starting to think about that now. We’re trying to figure out what organizations we can continue to work with when we leave the White House, how best to use the new platform as a former first lady. The President is thinking about the same thing,” Michelle Obama said.

“But the short answer to the question is, we’re going to keep doing that work and we’re going to figure out what are the best ways we can impact these issues.”

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The first couple have met with all seven architects in the running to design the Obama presidential library and museum, and on April 2 they hosted a dinner at the White House for foundation supporters, many of whom also have contributed to Obama’s campaigns and related causes.

A foundation official confirmed that Rogers, Sacks and Wolf were among those present at the April 2 White House dinner for the foundation.

The Chicago Sun-Times has learned that the attendees at that dinner also included: Chicago media executive Fred Eychaner, another major foundation donor; Chicago real estate mogul Michael Alter, also a partner in the Chicago Sky; and David Rubenstein, the co-founder and co-CEO of the Carlyle Group. Rubenstein donated $10 million to the National Museum of African-American History and Culture, set to open sometime in September on the National Mall.

Rogers, who is very close to the president and first lady, is the founder, chairman, CEO and chief investment officer of Ariel Investments in Chicago.

Sacks is chairman and CEO of GCM Grosvenor and is close to Mayor Rahm Emanuel. Sacks is vice chairman of World Business Chicago, a member of the Mayor’s Economic Council and a co-chair of the Mayor’s Plan for Economic Growth and Jobs. Sacks is an investor in the company that owns the Chicago Sun-Times.

Robert Wolf is founder and CEO of 32 Advisors in New York City and chairman of Measure — Drone as a Service.

“I am pleased to be joining the Board of Directors for the Obama Foundation,” Rogers said in a statement. “It was an honor to be a part of the Presidential Inaugural Committee in 2009, and I feel I am coming full-circle by joining the Foundation. I grew up on the South Side of Chicago and I’m looking forward to working with the Foundation to help promote opportunity and bring positive change to Chicago and to the world.”

“I’m honored to be a part of a foundation that will have a significant global impact and serve as an important asset for the city of Chicago,” said Sacks, a resident of Chicago and Highland Park.

According to foundation disclosures — which only broadly reveal the scope of donations — Sacks and his wife, Cari, gave between $500,001 and $1 million to the foundation. Rogers and Victoria, his daughter, gave between $250,001 and $500,000; Wolf and his wife, Carol, donated between $100,001 and $250,000.

In July 2015, the foundation board expanded to seven, with the addition of John Doerr, Thelma Golden and Julianna Smoot. Billionaire Doerr is a venture capitalist; Golden is the director of The Studio Museum in Harlem. Smoot was a member of the original foundation board. She stepped down in July 2014 to become a paid fundraising consultant for the foundation, with the deal ending in May 2015.

The other board members are David Plouffe, now an executive with Uber, who managed Obama’s 2008 campaign; Obama’s half-sister, Maya Soetoro-Ng; and J. Kevin Poorman, a Wilmette businessman, who took over several companies run by Commerce Secretary Penny Pritzker when she stepped down to join Obama’s Cabinet.