When bringing in the real deal isn't possible, it seems a former US president makes for a decent Santa substitute.

Key points: Mr Obama met with patients and their families at Washington hospital

Mr Obama met with patients and their families at Washington hospital The former US President acted as a "stand-in" for Santa, handing out presents to children

The former US President acted as a "stand-in" for Santa, handing out presents to children First Lady Melania Trump also visited the hospital last week

Barack Obama paid a surprise visit to the Children's National Medical Center in Washington DC, bringing with him a sack of presents for the young patients.

Mr Obama was given a rock star's entrance as he entered the hospital, with his swagger giving way to dance moves as he neared the singing crowd.

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Video of the visit was posted to the hospital's Twitter account, with the clip being viewed more than a million times in three hours.

"Thank you @BarackObama for making our patients' day so much brighter," the tweet said.

"Your surprise warmed our hallways and put smiles on everyone's faces."

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Wearing a red Santa hat, Mr Obama toured the hospital, meeting with patients and their families.

"Merry Christmas and happy holidays to the extraordinary kids, families, and staff at Children's National," he said in a tweet.

"And thanks for humouring me as your stand-in Santa."

US First Lady Melania Trump also made a trip to the hospital last week, reading patients a Christmas story during her visit.

She then gave each child a copy of the book, which was about a bullied Christmas ornament.

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Ms Trump did not wear a Santa hat for the visit, instead opting for a red-and-white coat and candy-cane striped stilettos.