Campaign and Russian agents.
MAGAs have no clue when it comes to subtlety and. nuance…the GOP Senators were not required to make a criminal judgment…just present the facts…so that’s what the 9 of them did (or create a firestorm in their party). The 8 Democrat Senators were not so encumbered, so they presented the factual evidence…and the logical conclusion…I.e. Collusion between Trump and Putin.