Sen. Cory Booker (D-NJ) told MSNBC’s Chris Hayes Tuesday evening that the NFL players who kneel during the national anthem “are not just taking a knee because they want to disrespect the flag. They're doing this because of real issues in this country.” He said that “protest is patriotism” and added that someone who says they’re more patriotic than someone else has “a shallow patriotism that seeks more to divide, demean, degrade others and lift themselves up,” while “a real patriot” finds ways to “advance our country.”

“Nonviolent protest is important and has always been to advancing our nation from Muhammad Ali to artists and entertainers who participated in movements from the women’s rights movement, the civil rights movement, the noble tradition in our country of protest,” Booker told Hayes.

“You have to understand these folks are not just taking a knee because they want to disrespect the flag. They're doing this because of real issues in this country that even the former head of the FBI gave a speech talking about implicit racial bias in policing," he added.

“As soon as someone tries to tell an American in this country that I'm more patriotic than you or to look down on your loyalty to this country,” Booker concluded, “please understand that says much more about that person's patriotism than theirs because their patriotism is a shallow patriotism that seeks more to divide, demean, degrade others and lift themselves up than doing what a real patriot should be doing in America is finding ways to advance our country and unite this nation to greater understanding and a more courageous empathy."

Refusing to stand during the anthem is not a popular form of protest among many of the NFL's viewers. A CBS poll found that 72 percent of Americans consider anthem kneeling “unpatriotic” and another recent study found that 34 percent of Americans are less likely to watch NFL games due to the protests.

Former 49ers quarterback Colin Kaepernick knelt during the anthem last year as a protest of police brutality.

"I am not going to stand up to show pride in a flag for a country that oppresses black people and people of color," Kaepernick told NFL Media in an interview at the time. "To me, this is bigger than football and it would be selfish on my part to look the other way. There are bodies in the street and people getting paid leave and getting away with murder."

Various NFL teams protested Sunday after President Trump tweeted that the NFL should fire players who knelt for the anthem. One hundred and fifty players knelt during the anthem Sunday.