After turning over the White House this month to a successor who aims to scuttle some of his key initiatives, President Barack Obama and his foundation will embark on an epic endeavor — racing for mega-donors who can rocket-launch their fund drive for a presidential library and museum on Chicago's South Side.

The scale is daunting: While Obama's library planners decline to provide a cost estimate, the George W. Bush library and endowment broke records at more than $500 million, the latest example of skyrocketing costs. Adding to the pressure, the Obama project is the first to be built under sharply increased federal requirements for a sustaining endowment. Obama chose to add another hurdle by pledging not to personally raise money for the project during his term in office.

So, the not-for-profit Obama Foundation faces a steep climb.

And a wild card hovers: What will the election of Republican Donald Trump mean for the fundraising campaign?

The first post-presidential year will be pivotal, experts say.

“The success of a really big campaign like this hinges on a small number of very large gifts at the beginning,” said David Jones, who raised money for former President George H.W. Bush's library in College Station, Texas, and now heads the facility's foundation.

He is among a number of observers who think Trump's victory may actually assist with some of the heavy lifting that lies ahead for Obama's Democratic loyalists.

“His friends know there needs to be an institution that will keep his legacy and his accomplishments very much alive,” Jones said. “If they don't do it through the library, the risk is his legacy could get dismantled. If I were involved in this campaign, that's what I'd be saying to the donor prospects.”

The Chicago-based Obama Foundation declined to comment on fundraising efforts.

Typically, fundraisers for presidential libraries find their lead donors from among the biggest supporters to election campaigns and inaugurals. In Obama's case, the pool is deep. He lifted the bar for presidential campaigns, raising nearly $750 million in 2008 and $722 million in 2012.

“There are a lot of rich, liberal donors who ... will open up their checkbooks,” said presidential library expert Benjamin Hufbauer, an associate professor at the University of Louisville.

As well, Obama “is going to be leaving the presidency with (robust) popularity numbers, and Michelle Obama is a rock star in her own right,” said James “Skip” Rutherford, who was local planning coordinator for the William J. Clinton Presidential Library and Museum in Little Rock.

Over the course of his swift political rise, Obama garnered support from Hollywood giants like DreamWorks co-founders Steven Spielberg, David Geffen and Jeffrey Katzenberg as well as from business titans like Warren Buffett and George Soros. One of Chicago's Hyatt heirs, the billionaire Penny Pritzker, his commerce secretary since 2013, was a lead fundraiser for his first presidential campaign.

Early money for the library project has flowed from a coterie of friends and supporters, among them tech executives, venture capitalists, real estate developers and foundations, including one started by Star Wars creator George Lucas, whose own plans for a museum in Chicago fizzled last year. Among the big local donors, at $1 million each as of year-end 2015, are the media tycoon Fred Eychaner, the Joyce Foundation and hedge fund executive Michael Sacks, a close ally of Chicago Mayor Rahm Emanuel. The mayor formerly served as chief of staff in the Obama White House.

Still, the fund drive promises to be arduous.

Money raised for former President George W. Bush's library and endowment exceeded $500 million, more than double the price for the Clinton library and more than quadruple the cost of the senior Bush's library. And this was achieved despite the younger Bush's low popularity ratings when he left office. The escalation is fueling speculation about the cost for the Obama center.

Some Washington experts think the change of political party in the Oval Office spells trouble for Obama's fundraising.

“Had a Democrat won in 2016, Obama would have access and direct influence over the White House and administration policies,” said Craig Holman, an expert in government ethics with Public Citizen, a watchdog group. “With a Trump victory, Obama really is cast as an outsider once he leaves office. He doesn't have the means of providing much in return to donors.”

White House press secretary Josh Earnest in May rejected any suggestion that a donation to the foundation could guarantee access.

“The president has made a commitment that he will not be raising money for the foundation while he's still in office,” Earnest said at a news conference. “What we have said about donors to the (election) campaign also applies to donors at the foundation, and it's simply this: Donating in support of the president's foundation does not guarantee you a meeting with the president of the United States. It also doesn't prevent you from getting a meeting with the president of the United States.”

He was responding to findings this year by MapLight, a not-for-profit that tracks political contributions, that 15 of 39 named donors to the Obama Foundation visited the White House for small meetings or events with the president, including all donors whose family or foundation had donated more than $100,000.

The Obama Foundation has taken a number of steps aimed at avoiding the sorts of roiling controversies that have singed the Clinton Foundation's fundraising efforts.

While Obama remains in office, the foundation agreed not to accept contributions from for-profit entities, federal lobbyists, or foreign nationals or agents.

“We are limiting our fundraising now to a group of longtime supporters of the president and limiting the amount that they can contribute,” Martin Nesbitt, chairman of the Obama Foundation, told reporters last summer. “But when the term is over, we will modify that in a way that facilitates us getting to our fundraising goals.”

The foundation also reports quarterly all donors and donations of more than $200. More specific information on major donors — addresses and donation totals — eventually becomes available on the foundation's annual tax returns. A total of $7.3 million was raised in 2014 and 2015, the first two years. The total to date in 2016 cannot be discerned from the donor list on the foundation's website.

The Obama Presidential Center, which will include a library, museum and offices in Jackson Park on the South Side, will be the 14th presidential library in a system founded in 1939 by the National Archives and Records Administration. Several more libraries pre-date that program.

kbergen@chicagotribune.com