While a fellow traveler – however detestable – is merely someone who sympathizes with an adversarial foreign power, a fifth columnist is someone who actively cooperates – colludes, one might say – with a hostile foreign state.
For all the talk of no collusion (styled as NO COLLUSION in a bigoted authoritarian’s tweets), Trump at last admits his willingness to collude with a foreign state against democratically-chosen American candidates:
Those who support Trump do so either despite of his desired collaboration with foreign (and dictatorial) powers, or because of it (hoping that they would benefit by the replacement of democracy with a herrenvolk). Either reason places their politics outside a traditional democratic order.
Trump isn’t merely another politician, and this isn’t merely another time. Towns, cities, states, and the country all face the same threat to the our democratic tradition.