Pete Carroll is not slamming the door on the Seattle Seahawks signing Colin Kaepernick -- claiming "the discussion and the opportunity is still open."

Of course, there's definitely a backstory here ... Seattle pulled the plug on a workout with Colin earlier this month because he wouldn't agree to end his kneeling demonstration. 

But, Carroll appeared on Sports Radio KJR on Thursday and essentially said Colin was still in the mix. 

"We are trying to figure it out," Carroll said ... "The discussion and the opportunity is still open."

"We're just trying to figure out what's best for us."

Carroll said he hadn't spoken with Kaepernick yet and was "not going there" when asked specifically about Colin's protest. 

Carroll did make a point to say his organization has been supportive of players who are trying to put a spotlight on social issues.