He was griping at the guards and complaining incoherently about his lawyers.
Because I'm partisan, I'll feature the griping from the Democratic side of the aisle.
He was an insider who insisted on being an outsider—and then on griping about it.
Old English gripan "grasp at, lay hold, attack, take, seek to get hold of," from Proto-Germanic *gripanan (cf. Old Saxon gripan, Old Norse gripa, Dutch grijpen, Gothic greipan, Old High German grifan, German greifen "to seize"), from PIE root *ghreib- "to grip" (cf. Lithuanian griebiu "to seize"). Figurative sense of "complain, grouse" is first attested 1932, probably from earlier meaning "gripping pain in the bowels" (c.1600; cf. bellyache). Related: Griped; griping.
late 14c., from gripe (v.). Figurative sense by 1934.
v. griped, grip·ing, gripes
To have sharp pains in the bowels. n.
gripes Sharp, spasmodic pains in the bowels.
A firm hold; a grasp.
[ultimately fr griping of the gut, ''colic, bellyache, stomach cramp'']