Sam had dinner on Saturday with Dave Kopay, a former NFL player who said he was gay in 1975 -- three years after his playing career ended.
On Sunday night, the NFL released a statement supporting Sam.
"We admire Michael Sam's honesty and courage," NFL senior vice president of communications Greg Aiello said in the statement. "Michael is a football player. Any player with ability and determination can succeed in the NFL. We look forward to welcoming and supporting Michael Sam in 2014."
Among other male pro athletes who have said they are gay, Jason Collins, a 12-year NBA veteran, came out in a Sports Illustrated article at the end of the 2012-13 regular season, but has not played for a team since. Midfielder Robbie Rogers became first openly gay male athlete to play in a U.S. professional team sports league when he entered a MLS game in May 2013.
Conner Mertens, a kicker for Willamette University, last month became the first active college football player in the U.S. to come out publicly.
Sam said that he realizes his revelation may engender a variety of reactions in the football world. "There will be negativity, negative reactions," he said. "I expect that. ... Everyone can say hurtful things and hateful things; I don't let stuff like that distract me. But there are going to be positives. The positives will outweigh the negative."
Sam led the SEC with 11.5 sacks, and 19 tackles for a loss. Most NFL draft projections see him as a likely mid-round pick, with some saying Sam could go as high as the third round, with a possible position switch to outside linebacker. He is rated as the 12th-best outside pass rusher in the draft by ESPN Scouts Inc.
"I just want to go to the team who drafts me," he said, "because that team knows about me, knows that I'm gay, and also knows that I work hard. That's the team I want to go to."
Sam said that despite some comments from current players, he doesn't anticipate difficulty gaining acceptance in an NFL locker room.
"Hopefully it will be the same like my locker room," he said. "It's a workplace. if you've ever been in a Division I or pro locker room, it's a business place. You want to act professional."
Sam rejects the appalling slanders that sometimes have been hurled at gay men.
"I mean, people will talk about the stereotype of gays being in the locker room ... to me, I think that it's a little stereotyped that gay people are predators. It's just very offensive."
Other such negative stereotypes seem too absurd for him even to consider.
"If you led the SEC with 11.5 sacks and 19 tackles for losses?" he said, laughing. "If a gay person did that, I wouldn't call that person weak."
Just last week, he said, he came out to his parents, during a phone call.
"I told my mom and dad last week, and they just pretty much said, 'We knew and we love you and support you,' " he said. "I'm their baby boy. I'm the first to go to college. I'm the first to graduate college. Something like this is just another milestone.
"And I love my hometown. I think when this story breaks, I think they're just going to love me even more for who I am."
Sam understands that his life is about to change forever; he said he is happy and proud to be speaking out at last.
"I'm not afraid to tell the world who I am. I'm Michael Sam: I'm a college graduate. I'm African American, and I'm gay," he said. "I'm comfortable in my skin."