When asked whether he condemned right wing supremacists in the first Presidential debate with Biden, Trump responded with what sounded like a rallying cry to the right wing.
Note that he quickly moved on to condemn Antifa, in what seemed a mobilising manoeuvre against dessenting groups.

When later challenged, he denied knowing anything about the 'Proud Boys'... though he very clearly and deliberately quoted the PB moto... 'Stand Back, Stand By'.
Just a lucky punt? I don't think so!!