the.com/mudslinging

means The practice of attacking an opponent's character or reputation with insults and accusations instead of debating the actual issues.

from Literal before it was political — early American English used 'sling mud' for throwing filth at someone, a crude physical insult. By the mid-1800s, 'mudslinging' had splattered into politics, describing campaigns that smeared rivals with scandal and rumor rather than arguing policy. The metaphor works because it's so physically obvious: mud is cheap, easy to grab, and even if it doesn't stick, it still leaves a stain.