Opponents seized on his slip of the tongue to make a big issue of it.
Tips
usage
Literally 'to write a big essay (about it)'. Always negative: someone is exploiting a small issue, exaggerating it, or twisting it into political/rhetorical ammunition. Common in news commentary about diplomatic disputes, media controversies, and political opponents seizing on missteps.
memory
Imagine someone handed a tiny detail and turning it into a long classical essay (文章) — vastly more text than the topic deserves. That gap between the trivial subject and the grand treatment is the whole point.
