LOS ANGELES — In the five years since he last played in an N.F.L. game, Colin Kaepernick, the former San Francisco 49ers quarterback who ignited an international debate on athletes’ right to protest, has only sporadically surfaced in public. Accepting an award here, or rolling out a Netflix series there, Kaepernick has in those calculated appearances always affirmed that he was “staying ready” for a return to football.

This month, he has taken a new approach, organizing pop-up workouts that are often scrapped together in less than 24 hours in cities across the country. On Friday at U.C.L.A.’s practice facility, most of the receivers who fielded his passes were still in high school or enrolled in junior colleges. Last week in a workout posted to his Instagram account, Kaepernick threw to Seattle Seahawks receiver Tyler Lockett in Arizona, after plotting to meet via Twitter.

In workouts in Atlanta, New Orleans and three other cities, he corralled workout partners with a range of experience through previous connections and word of mouth using the sessions as a public forum to showcase his talents and potentially solicit an N.F.L. audition.

“In the past, we tried to approach things very quietly behind the scenes — just stayed ready, kept working and had my agent have conversations,” Kaepernick told The New York Times in a brief interview. “But there’s been a persistent question of, ‘Is he ready? Can he still play?’” He said publicly documenting his workouts, being ready to throw on the fly — to anyone, anywhere — is his way of answering those questions.

Kaepernick’s workouts have come at a ripe time in the league’s calendar, the heart of the free agency period, when N.F.L. teams have hastened to trade, sign, and re-sign quarterbacks who might improve their fortunes. This month, Russell Wilson was traded to the Broncos after 10 seasons with the Seahawks, Matt Ryan left the Falcons for the Colts, and the Browns traded for Deshaun Watson. In a news conference introducing Watson, the team’s General Manager Andrew Berry answered a flurry of questions about how extensively executives looked into accusations of sexual misconduct brought against the quarterback by two dozen women before Cleveland signed him.

While out of the league, Kaepernick has kept busy with various enterprises. He was the face of a popular Nike ad campaign in 2018, and has launched a number of media endeavors, founding a publishing company in 2020 through which he plans to release a memoir. In 2021, he premiered a Netflix docuseries based on his life, “Colin in Black & White,” that he created with the director Ava DuVernay. Kaepernick has also worked extensively with his “Know Your Rights Camp,” an activist group he founded that describes its mission as advancing “the liberation and well-being of Black and Brown communities” and which offers free secondary autopsies for families of people who died under “police-related” circumstances.

Now at 34-years-old, Kaepernick is making his most pronounced argument to teams which have not been able to confidently assess the more simple concerns about his playing ability. By posting video footage of his workouts on social media, Kaepernick has made for himself the highest-profile audition reel for teams since an October 2019 showcase ended with a chaotic dispute with the N.F.L. The quarterback abruptly canceled a planned workout for all 32 teams at the Atlanta Falcons’ training facility because of a disagreement over a liability waiver the N.F.L. would have had him sign and the league’s resistance to having media attend. Instead, Kaepernick threw at a local high school in front of eight scouts, but was not signed.

Kaepernick called his current road trip “the best approach that we have at this point,” a proactively engineered campaign while there are favorable conditions in the league for his potential return. David Robinson, a trainer and workout partner for Kaepernick, has said five franchises have inquired about the quarterback, but only one has publicly shown interest.

During a news conference March 16, Seahawks Coach Pete Carroll said — unprompted — that he thinks Kaepernick deserves a second shot in his first public comments since trading Wilson. At his workout a week later at Washington, Kaepernick told reporters that he spoke with Carroll and General Manager John Schneider and was hopeful for another audition in Seattle, which previously worked him out in 2017.

Wearing a black, sleeveless Nike shirt and shorts on Friday, Kaepernick threw for nearly two hours with about 20 other people at U.C.L.A. The velocity on his passes looked strong, albeit not against live competition, as he rolled out and zipped darts to receivers along the sidelines. He also placed nice touch on deep passes toward the end zone, but misfired on a pass that led a receiver too far to the left on a post route.

During breaks, Kaepernick acted as an informal coach to Justyn Martin, a freshman quarterback at U.C.L.A., who threw next to him during the session.

“There wasn’t a moment where he broke out of focus,” Martin said. “He was kind of the same person the whole workout. Just seeing how he conducts himself, how he sets the tempo and me getting to soak in all of his expertise, it was great.”

Henry Organ, a sports agent based in Oakland, Calif., said he received a call from a former colleague at Nike at 4 p.m. on Thursday asking if he could secure field access and potential receivers for Kaepernick’s workout the next day.

Organ immediately called a strength and conditioning coach at U.C.L.A., who offered up the school’s practice field and weight room. But with few student athletes on campus during spring break, Organ, with help from the Hall of Fame wide receiver Terrell Owens and Najee Lovett, a former player at Idaho, contacted pass catchers they knew in town who may be available. Kaepernick landed in Los Angeles around midnight on a commercial flight, slept in a nearby hotel and was ready to throw to whomever by Friday morning.

Organ said he was grateful to do what he could to help Kaepernick’s effort on short notice.

“Seeing a Black quarterback that’s still very talented, I feel like I did my part in history,” he said. “I can’t make him perform. I can’t make a team sign him.”

At the height of Kaepernick’s career, he led San Francisco to a Super Bowl appearance, two N.F.C. Championship berths and set an N.F.L. record for most rushing yards by a quarterback in a playoff game. But his résumé has long been overshadowed by his protest, first when he began kneeling during the national anthem in protest of police brutality in 2016, and later as he fought the league for his place on a roster.

Kaepernick has gone unsigned after opting-out of his contract that off-season, when he became a lightening rod for a cultural divide over whether his spotlighting social inequities disrespected the military. In 2017, then President Donald J. Trump profanely chastised players who knelt and said they should be fired, while athletes across sports took up kneeling. In 2019, Kaepernick and a former teammate, Eric Reid, settled a lawsuit with the N.F.L. that argued the 32 team owners had colluded to keep him out of the league.

But after the killing of George Floyd sparked a national reckoning on race, which saw game stoppages in sports and protests in streets across America, reception to athletes’ criticisms of systemic inequality has shifted.

In June 2020, when several Black N.F.L. players collaborated on a video posted on social media in which they promoted the Black Lives Matter movement, N.F.L. Commissioner Roger Goodell was pushed to condemn the league’s initial handling of players’ peaceful protests in a separate video. In a seeming reference to Kaepernick’s protest, Goodell stated, “We, the National Football League, admit we were wrong for not listening to N.F.L. players earlier and encourage all to speak out and peacefully protest.”

Still, Kaepernick remains a free agent and it is not clear whether his cross-country tour has generated interest or just buzz.

“I miss the preparation. I miss the team aspect and the camaraderie,” Kaepernick said. “But being able to do this gives me a little bit of that in the process.”