US president Barack Obama has reiterated his support for Missouri Tigers defensive end Michael Sam following his decision to publicly announce that he is gay.

Sam made the revelation during a television interview last Sunday, meaning that he would become the first openly gay player in NFL history if he is chosen in May's Draft.

Obama took to Twitter to back Sam immediately after the initial announcement and echoed his support for the 24-year-old on Sunday.

"I really like the fact that Michael did it before the draft because his attitude was, 'You know what, I know who I am. I know I can play great football and judge me on the merits,'" Obama told TNT.

Sam, who will take part in a scouting camp later this month, has been projected as a mid-round Draft pick.