WASHINGTON – Despite predictions of freezing temperatures this weekend, U.S. Olympian and long-distance runner Meb Keflezighi will lead the annual Credit Union Cherry Blossom Ten Mile Run and 5K walk on Sunday, trailed by about 15,000 participants, organizers said Thursday.

The race will proceed although modifications may be needed depending on how bad the weather is, the organizers said at a news conference.

Participants will run along Rock Creek Parkway and the Potomac River, finishing near the Tidal Basin. This year, the Congressional Federal Credit Union and the U.S. Senate Federal Credit Union will donate $380,000 to the Children’s Miracle Network Hospitals as part of the event; this is the 17th year the two credit unions have sponsored the event.

Keflezighi, who won the silver medal in the 2004 Olympic marathon, is returning as this year’s celebrity runner, a role he first took on in the 2016 race. He is the first American man to win both the New York and Boston marathons in more than 20 years.

He will act as a pacer, meaning he won’t race competitively, but instead guide about 300 to 400 runners hoping to finish in under an hour.

“I’ve always wanted to do this race (competitively) for a long time but because of the Boston Marathon two weeks later, I was never able to be a lead athlete,” said Keflezighi. “To be a part of the history and what’s going on in D.C., it’s huge deal to be here and able to run it.”

Runners are generally matched in groups called corrals based on their anticipated race times.

Because of the Capitol Hill credit unions’ long-time support for the race, it has become a tradition among congressional staffers. This year, more than 600 staffers and 55 teams from Congress are competing.

He said runners should focus on their goals for the race.

“We don’t know what your financial outlook is or what your political beliefs are,” said Keflezighi. “You’re a runner for 10 miles, that’s the beauty of it.”