To wrangle is to take part in a long, angry, intense argument, especially over an issue with lots of details. You can also wrangle, or herd, a bunch of cows. Politicians and lawyers frequently wrangle, no cows necessary.
Wrangle in its current meaning comes from the nineteenth century American term wrangling, the art of herding cattle, probably with the idea in mind that rounding up those tiresome details is a bit like rounding up all those tiresome cattle; they tend to go flying off in all directions. From wrangler in the cowboy sense we get Wrangler jeans, though not all wranglers wear Wranglers of course.