Dallas, Texas (CNN) Pete Buttigieg endorsed Joe Biden on Monday, but it was the former Vice President who arguably paid his one-time competitor the bigger compliment.

After Buttigieg lauded him and urged his supporters to back the former vice president, Biden took the mic and compared the 38-year old former mayor of South Bend, Indiana, to Beau Biden, his late son and someone who the former vice president refers to as his "soul."

"I don't think I've ever done this before, but he reminds me of my son, Beau," Biden said, with Buttigieg looking on.

The former mayor lowered his head at the comment, seemingly taken aback by the power of what Biden was saying.

"I know that may not mean much to most people, but to me, it's the highest compliment I can give any man or woman," Biden continued.

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