Kaepernick 'Exercising His Constitutional Right,' Says President Obama

Kaepernick's protest has shown signs of spreading to other players and sports.

"I don't doubt his sincerity," Obama said of Kaepernick, before going on to say generating conversation on the topic was positive.

The conversation Kapernick has generated -- about race, patriotism, sports protest and violence by and against police -- has not been received positively by all Americans.

Santa Clara Police Chief Michael Sellers offered a rebuke of that position on Saturday, saying that "officers are here to protect the rights of every person, even if we disagree with their position," but also expressed sympathy for the union's sentiment.

He is also now the top-selling 49er in terms of jersey sales, after being ranked as low as 20th, prior to news of his protest spreading, as first noted by San Jose Mercury News.

It remains to be seen whether Kaepernick's protest of the anthem will gain public momentum, but other athletes have joined him in his actions, including fellow NFL players like Jeremy Lane and Doug Baldwin Jr. of the Seattle Seahawks, and Russell Okung of the Denver Broncos.

Seattle Reign midfielder Megan Rapinoe knelt during the national anthem Sunday night before a game against the Chicago Red Stars in the National Women's Soccer League, and expressed solidarity with Kaepernick after the game while speaking to the press.

"I'm disgusted with the way Colin has been treated and the fans and hatred he has received in all of this," Rapinoe told ESPN's Julie Foudy.

Obama said, before giving his answer about Kaepernick, that he hadn't been thinking about football lately. The NFL regular season opens this week, and the 49ers are scheduled to host the Los Angeles Rams in a game on Monday, September 12.

Kaepernick is expected to continue to protest the anthem at that game.