WASHINGTON — Opening his first White House Easter Egg Roll, President Trump extolled the strength of America as thousands of children and some adults reveled in the tradition of rolling hard-boiled eggs across the manicured lawn in his backyard.

‘‘This is the 139th Easter Egg Roll. Think of it, 139,’’ Trump said Monday.

‘‘And we will be stronger and bigger and better as a nation than ever before. We’re right on track,’’ he said, speaking of his nearly 100 days of leadership.

Trump’s wife, Melania, and their son, Barron, 11, and the Easter Bunny joined him on a balcony before they joined some of the 21,000 people who were expected to attend.

Trump thanked his wife for ‘‘working on this for a long time to make it perfect.’’

There was, however, some speculation about whether the Trumps would be able to pull off a successful ‘‘egg-stravaganza.’’ Planning seemed to get off to a late start, with the Trumps taking longer than previous administrations to announce Monday’s date.

At least one regular egg roll vendor took to Twitter to remind the White House that a deadline for ordering wooden eggs that are given out as souvenirs was approaching.

The egg-rolling event, which dates to 1878, was smaller this year, down from 35,000 ticket holders last year. A reading nook, an area to send messages to US troops, and a stage were retained.

‘‘As we renew this tradition, thank you for joining us,’’ the first lady said. Moments later, Trump blew a whistle three times, each time sending youngsters scurrying to use a wooden spoon to maneuver a dyed egg across a finish line. Trump, the first lady, and Barron joined kids to color cards to send to US service members.

Trump’s older sons, Don Jr. and Eric, and their wives and daughter Tiffany also attended.

Associated Press