President Joe Biden mixed up Taylor Swift and Britney Spears in remarks Monday during the White House’s annual turkey pardoning ceremony, which happened to fall on the president’s 81st birthday.

He was in the midst of pardoning two turkeys, Liberty and Bell, when he mistakenly used the name Britney in an apparent reference to Swift’s current international tour.

“Just to get here, Liberty and Bell had to beat some tough odds and competition. They had to work hard, to show patience, and be willing to travel over 1,000 miles,” Biden said.  “You could say it’s even harder than getting a ticket to the Renaissance tour or, or Britney’s tour. She’s down, it’s kind of warm in Brazil right now.”

Swift performed Sunday night in Brazil after postponing her Saturday show because of extreme heat in the country. Spears is currently not on tour.

The White House did not immediately respond to NBC News’ request for comment on Biden’s apparent mix-up, which comes as voters express concerns in polling about his age.

According to a recent poll from NBC News, Swift was found to be overwhelmingly well-known among voters, with 94% recognizing her name when asked.

Swift also raked in a high net favorability rating in the poll, with 40% of registered voters holding a positive view of her, compared to only 16% who have a negative opinion.

Even the star turkeys from Monday’s ceremony seem to love Swift, according to National Turkey Federation Chairman Steve Lykken. He said Sunday that Liberty and Bell had been listening to some music prior to the pardoning.

“I can confirm they are, in fact, Swifties,” he said.

The president’s apparent slip-up comes on his 81st birthday. In the same remarks, Biden joked about his age, saying, “As much of you know, it’s difficult turning 60.”

“This is the 76th anniversary of this event. I want you to know I wasn’t there, and I was too young to make it up,” he quipped.

NBC News’ latest poll finds Biden trailing behind former President Donald Trump among young voters ages 18 to 34, with 46% of them supporting Trump and 42% Biden.

The disparity is significant compared to Biden’s success among young voters in the 2020 presidential election, when he won voters ages 18 to 29 by more than 20 points, according to the national exit poll.

Another NBC News poll in September found 59% of Americans to hold major concerns about Biden having the necessary mental and physical health to be president for a second term.

Trump on Monday released a letter from his physician, who called the former president’s health “excellent” and said “his cognitive exams were exceptional,” but did not provide details on the exams.

The physician, Bruce Aronwald, said that Trump “reduced his weight through an improved diet and continued daily physical exercise,” though the letter did not say what Trump weighed previously or what he weighed during his most recent examination on Sept. 13.

Trump has previously drawn skepticism over assessments of his health. NBC News reported in 2016 that a different doctor wrote a letter on Trump’s health in just five minutes while a limo sent by Trump waited outside of the doctor’s office. That doctor, Harold Bornstein, wrote at the time that Trump would be “the healthiest individual ever elected to the presidency.”