WASHINGTON — Oprah Winfrey, a close friend of former President Barack Obama and former first lady Michelle, and one of the most successful entertainment executives in the world, has donated at least $1 million to the Obama Foundation, according to records posted on Monday.

The donation was expected, given her relationship with the Obamas, her historic role in the Obama election in 2008, their Chicago connections and her interest in the Obama Presidential Center, with its centerpiece museum.

Winfrey, who at the time avoided politics, helped Obama score crucial 2008 Democratic presidential primary wins over rival Hillary Clinton when she stumped for him in early voting states.

The exact amount of the Winfrey donation is not known because the Obama Foundation only posts broad ranges of gifts each quarter.

The foundation usually provides donor giving details in what had been, up until this year, its May annual IRS filing which covered contributions for the previous year. The Obama Foundation has delayed filing its IRS 990 report, telling the Sun-Times more preparation time was needed.

In April, the foundation had listed 47 gifts of at least $1 million. On Monday, there were 56 contributions of at least $1 million.

Winfrey, a major philanthropist, actress, theatrical producer and cultural and moral influencer donated $21 million to the National Museum of African American History and Culture and a theater in the building bears her name.

Earlier this year the museum on the National Mall opened a show, “Watching Oprah, The Oprah Winfrey Show and American Culture.”

It’s not clear yet if the Obama Foundation is using naming rights to woo mega donors as part of the drive to raise the hundreds of millions of dollars needed to build the Obama Center in Jackson Park and operate foundation programs.

This week, the Obama Foundation is hosting its African Leaders program in Johannesburg, South Africa. On Wednesday Obama will host a town hall with the “rising leaders,” numbering about 200.