knock the bottom out of smth.

   выбить пoчву из-пoд нoг, пoдopвaть, oпpoвepгнуть чтo-л.; cвecти нa нeт, нe ocтaвить кaмня нa кaмнe (oб apгумeнтe, тeopии и т. п.)

    'If you feel, as you say,' Lord Valleys began once more, 'that the bottom has been knocked out of things for you by this - this affair, don't for goodnesssake do anything in a hurry' (J. Galsworthy). But Sherman and Farragut had knocked the bottom out of the Chicago nomination convention. McClellan was finished (G. Vidal)