An essential element of persuasion is addressing the audience in terms of what they value. Are the impeachment managers speaking to what the Republican senators value? No.
The impeachment managers are calling for fairness, honesty, integrity, respect for the law and for the Constitution and for the nation. Are these values that Republican senators hold and are moved by? No.
That sounds like a snarky question but it isn’t. We know what someone values by their actions, not by their words. And the actions of the Republican senators tell us that their core value is to seize, hold, and protect the power to rule. Winning is the core value. All else is a distant second.
If the impeachment managers hope to win this persuasion argument, they must speak to how Republican senators can stay in power – or recover their lost power – or protect themselves from the loss of power. They need to demonstrate that the actions of the defendant threaten the ruling authority of these Republican senators.
This means that the winning argument to these Republican senators is a nakedly political argument. Show clear evidence that the defendant is a drag on an individual Senator’s chances of winning. Make that argument plainly on the floor of the Senate chamber. Make it personal. Show reliable polling results and trends. Leverage the outcome of the 2018 elections and the Republican losses in the House and in state governorships. Show voter disgust.
Yes, tie this turnaround back to the voter reaction to the defendant. But make the political argument in plain language to plainly political Republican senators. It’s the only argument that moves them. It’s all that Republican senators value.
… in my opinion.