Colin Kaepernick said the ball is in the court of the NFL and its 32 teams after he completed a rearranged workout in Atlanta on Saturday.
Former San Francisco 49ers quarterback Kaepernick has been out of the league since the end of the 2016 season, during which he attracted controversy by kneeling for the United States national anthem in protest against racial injustice and police brutality.
The NFL organised a workout for Kaepernick at the Atlanta Falcons training facility, which it said 25 clubs were set to attend.
However, a session initially scheduled for 15:00 local time (20:00 GMT) was relocated and pushed back to 16:00, with Kaepernick's representatives slamming the NFL for not providing "a legitimate process" and not allowing members of the media to attend and film the workout.
Members of the media did attend the re-arranged workout, with hordes of Kaepernick's supporters also intently watching the session, which was streamed on YouTube.
According to a report from ESPN's Adam Schefter, one NFL executive said Kaepernick displayed an "elite" arm.
Speaking afterwards to the assembled media, Kaepernick said: "Our biggest thing today was making sure we had transparency with what went on.
"I've been ready for three years, I've been denied for three years. We have nothing to hide. We're ready for the 32 teams to stop running, stop running from the truth. I've been ready, I'm staying ready and I'll continue to be ready.
"We'll be waiting to hear from [NFL commissioner] Roger Goodell, the NFL, the 32 teams. The ball's in their court, we're ready to go."
Before the workout, the NFL issued a statement responding to claims made by his representatives, including that he was asked to sign an "unusual" liability waiver.
"We are disappointed that Colin did not appear for his workout. He informed us of that decision at 2:30pm today along with the public," the statement read.
"Today's session was designed to give Colin what he has consistently said he wants -- an opportunity to show his football readiness and desire to return to the NFL. Twenty-five (25) clubs were present for the workout, and all 32 clubs, their head coaches, general managers, and other personnel executives would have received video footage of the interview and workout, shot by the Atlanta Falcons video crew.
"The NFL made considerable effort to work cooperatively with Colin's representatives. We invited his agent to suggest questions for the interview. Yesterday, when Colin's representatives said he wanted to bring his own receivers to the workout, we agreed to the request. In addition, coach Hue Jackson discussed with Colin's agent what drills would be run at the workout so that Colin would know what would be expected of him.
"Last night, when Nike, with Colin's approval, requested to shoot an ad featuring Colin and mentioning all the NFL teams present at the workout, we agreed to the request.
"On Wednesday, we sent Colin's representatives a standard liability waiver based on the waiver used by National Invitational Camp at all NFL Combines and by NFL clubs when trying out free agent players. At noon today, Colin's representatives sent a completely rewritten and insufficient waiver.
"We heard for the first time last night, around the same time we heard from Nike, that Colin wanted to bring his own video crew. We heard for the first time this afternoon that Colin wanted to open the event to all media.
"We agreed to have Colin's representatives on the field while the workout was being conducted and to allow them to see how it was being recorded. We did so even though we have been clear from the beginning that this is private workout. As is typical with NFL Combines, one video crew was prepared to shoot and distribute video of the interview and workout.
"We confirmed with Colin's representatives that they would receive both the video that would be sent to all 32 clubs as well as the raw footage from the entire event, which is unprecedented.
"Colin's decision has no effect on his status in the league. He remains an unrestricted free agent eligible to sign with any club."