Yes, RUS sources are the current major problem, as that 'govt' has been running an active measures campaign to undermine western democracies for close to two decades.

And those measures extend into both parties. They are specifically designed to maximize polarization, as polarization undermines democracy, and the assault on the truth makes everyone more malleable. People don't need to specifically buy into the dezinformatsiya (that's a mere bonus), the win is when people give up and say that the truth cannot be known, so disengage.

The fact is that one major party has fully bought into the active measures (and driven out those who don't go along), but the major wing of the other party is just as dependent on those measures, and that wing is also just as inclined towards authoritarianism if they get power.

The current fight is not between the parties, it is authoritarianism vs democracy.

Fighting dezinformatsiya is key to maintaining democracy and avoiding authoritarianism.