Is there a technical term for plotting or conspiring?
What you are describing is reminiscent of the personality trait called Machiavellianism. The construct was first described by Christie and Geiss in 1970, and refers to conduct that comports with the political philosophy of Italian writer Niccolò Machiavelli in 1532:
... manipulativeness and deceit, cynical views toward human nature, and a cold, calculating attitude towards others... cunning, deceit, and the notion that "means justify the ends.
From: Machiavellianism, Cognition, and Emotion: Understanding how the Machiavellian Thinks, Feels, and Thrives. Machiavellianism is part of what's called the dark triad of personality, which also includes narcissism and psychopathy.
I think Machiavellianism is as close as you'll get for what you've described. Here's an interesting study looking at personality ratings of Clinton and Trump by experts in US politics:
We also ﬁnd a substantial difference (d = 3.18, p < 0.001) on
emotional stability between the two candidates: if Clinton is perceived
as relatively high in this trait, Trump is, again, perceived as extremely
low. Finally, our results conﬁrm Trump's high scores for perceived
narcissism and psychopathy. On those two traits Clinton is assessed as
relatively average (d = 2.06 and 1.84, respectively; p < 0.001). For
Machiavellianism as well our experts rated Trump more severely than
Clinton (d = 1.51, p < 0.001).
Nai, A., & Maier, J. (2018). Perceived personality and campaign style of Hillary Clinton and Donald Trump. Personality and Individual Differences, 121, 80-83.