WASHINGTON- Former Democratic U.S. President Barack Obama has scaled back plans to celebrate his 60th birthday this weekend, a spokeswoman said on Wednesday, citing the spread of the highly contagious COVID-19 Delta variant.

The outdoor event has been in the works for months, planned in line with public health guidelines and COVID safeguards, Obama spokeswoman Hannah Hankins said.

"Due to the new spread of the Delta variant over the past week, the President and Mrs. Obama have decided to significantly scale back the event to include only family and close friends," Hankins said in a statement.

"President Obama is appreciative of others sending their birthday wishes from afar and looks forward to seeing people soon."

Obama, who turned 60 on Wednesday, had planned to mark his milestone birthday at his Martha’s Vineyard home on Saturday with hundreds of former Obama administration officials, Democratic donors and celebrities, according to reports.

Stars including George Clooney and Oprah Winfrey as well as White House chief of staff Ron Klain had been among the expected attendees, the New York Post and the New York Times reported. Klain, now President Joe Biden’s top aide, changed his mind and decided not to attend, the Times said.

Hawkins did not provide details on the scaled down plans.

Obama's planned gathering drew media attention as the United States once again grapples with rising COVID-19 cases that have pushed hospitals to capacity and caused some local officials to re-impose some restrictions.

On Tuesday, Biden called on governors to step up efforts to contain the rapid spread of the Delta variant and backed efforts by businesses, universities and other entities that are imposing mask mandates, vaccine requirements and other measures.

Biden served as vice president under Obama, who left office after two terms in January 2017.

(Reporting by Susan Heavey; Editing by Doina Chiaacu and Steve Orlofsky) ((sheavey@thomsonreuters.com; +1-202-898-8300;))