might and main, with

(with) might and main

With as much effort or strength as one can muster. She attacked that punching bag with might and main. If you're not happy in your current job, then you should be working might and main to find a new one.
See also: and, main, might

might and main, with

Strenuously, vigorously, as in She pulled on the rope with all her might and main. This expression is redundant, since the noun main also means "strength" or "power." It survives only in this phrase, which may also be dying out. [Late 1200s]
See also: and, might