ATLANTA – Four months into quarterback Colin Kaepernick’s 2017 free agency and heading into intensified criticism from President Donald Trump over player protests, the NFL used a Washington consulting firm to ask Americans whether Kaepernick should have been signed by a team, according to sources familiar with the league’s research.

The poll was conducted by The Glover Park Group, a consulting firm that was co-founded by then-NFL communications chief Joe Lockhart, sources told Yahoo Sports. The data sought by the NFL included fan attitudes about a few high-profile league concerns, including domestic violence, gambling, player protests and player safety. Sources noted that Kaepernick was the only player singled out in the research for specific opinions, which were then compiled and sent to various league officials, including commissioner Roger Goodell and several other high-ranking executives.

The poll could create a significant point of contention in Kaepernick’s collusion complaint against the NFL, raising the question of why the league conducted opinion research with its fan base about the former San Francisco 49ers quarterback. The existence of polling data on Kaepernick could also raise the question of whether the research went beyond high-ranking NFL executives to ownership groups or other team personnel who could have signed the quarterback.

Colin Kaepernick has an ongoing grievance against the NFL. (Getty Images) More

When asked about Kaepernick’s inclusion in the GPG poll, the NFL declined comment through a spokesperson. Representatives for Kaepernick and the NFLPA both declined immediate comment.

According to sources, the NFL approved research that sought two pieces of information: Whether Americans believed Kaepernick should have been signed by an NFL team; and given that Kaepernick remained a free agent, whether fans believed that was because he refused to stand for the national anthem or due to his on-field performance or other reasons.

The sources said the poll also explored overall attitudes toward the potential disciplining of players who refused to stand for the anthem in protest over racial and social inequalities. That data was then divided into multiple demographics, sources said, including whites, African-Americans and Latinos, Democrats, Republicans and independents, and Baby Boomers, Generation Xers and Millennials.

The sources declined to share specific numbers, but said the poll revealed a deep racial, political and generational division when it came to player protests. Specifically, divisions in which a majority of white NFL fans supported disciplining players for not standing for the anthem versus a majority of the NFL’s African-American and Latino fans who didn’t. The sources also said a majority of Republican NFL fans supported the disciplining of players versus a majority of Democrats who didn’t, and a majority of Baby Boomer NFL fans significantly supported discipline more than both Generation Xers and Millennials.

The polling data harvested in the summer of 2017 – showing that white NFL fans supported discipline far more than African American NFL fans – provides a more nuanced backdrop for the memo Goodell sent to NFL teams on Oct. 10, 2017. It stated, “The current dispute over the National Anthem is threatening to erode the unifying power of our game.” That same memo also went on to discuss fan attitudes, saying “Like many of our fans, we believe that everyone should stand for the National Anthem.” Ultimately, the memo from Goodell to teams didn’t contain language reflecting the specific racial and political divide among fans over disciplining players who don’t stand for the anthem.

Days after that memo from Goodell, Kaepernick filed a complaint against the league and owners, accusing them of colluding to keep him from signing with a franchise due to political pressure related to his gameday protests. That complaint has resulted in an ongoing run of discovery and depositions that have included a number of NFL power brokers, including Goodell.

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