Beto O'Rourke -- the congressman who went viral defending NFL kneelers -- says he's totally fine with people boycotting Nike ... because it's another form of nonviolent protest.
Beto is currently in a very tight senate race in Texas against incumbent Ted Cruz -- and his speech on the NFL protesters has become a major issue between the two candidates.
So, when we saw O'Rourke in D.C. on Friday -- we had to ask about the outrage over Nike's new ad featuring Colin Kaepernick ... which inspired some people to burn their shoes and cut Swooshes out of their socks.
"I think it's fine for people to do that," O'Rourke tells TMZ Sports ... "I think that's a peaceful, nonviolent way to protest a decision that you disagree with, which again comes back to the genius of this country and our democracy."
As far as his personal feeling about the Kaepernick ad -- Beto says, "Good for Nike."