One of the organizers of this week's Tight End University said Tim Tebow did not get an invitation to participate because of a higher-than-expected response that meant there wasn't enough room.

San Francisco 49ers tight end George Kittle -- who along with the Kansas City Chiefs' Travis Kelce and former player Greg Olsen is conducting TEU -- said on ESPN's First Take on Tuesday that he eventually hopes to open the event to every tight end in the NFL but couldn't justify inviting Tebow over more experienced players.

"If I can't invite every tight end, how do I not invite a second- or third-string guy on a team that's been playing tight end since he was 18 years old in high school?" Kittle said. "Nothing against Tim Tebow. I hope that he has incredible success this year. I hope he has 10 touchdowns. I hope he has a great year, but it's hard for me to invite someone to this that just started playing the position when I can't invite a guy that's been playing it for eight to 10 years. That's just hard for me."

Tebow is attempting a pro comeback at tight end after not playing in an NFL game since 2012 and not appearing in a training camp since 2015. Tebow was a quarterback then -- he was the 25th overall pick by Denver in 2010 -- but he called up Jacksonville Jaguars coach Urban Meyer and asked his former coach at Florida for a tryout at tight end.

Tebow worked out twice, and the Jaguars signed him on May 20.

Kittle said he was surprised at the amount of interest Tight End University received from players around the league. The event will be held Wednesday through Friday in Nashville, Tennessee.

"I want everyone to come because I want everyone to learn, everyone to get better," Kittle said. "But we didn't really plan that every single tight end would want to come. We thought we were going to get like 20, 25 guys max, and the next thing we knew we were at 45-50. Ran out of hotel rooms. Kind of ran out of space just in general.

"Hopefully in the next coming years I can make it available to every single person and then any tight end that wants to come can show up, learn, get better and just take another step forward."