house of cards
From Longman Dictionary of Contemporary Englishhouse of cardsˌhouse of ˈcards noun [singular] FAILa plan that is so badly arranged that it is likely to failExamples from the Corpushouse of cards• Or building a house of cards.• The whole model of race-linked characteristics ensuring success in sport has the solidity of a house of cards.• Alongside the urge to blow down the house of cards comes a tender impulse towards reconstruction.• If the house of cards that is the budget agreement should shiver, skin the Madagascarians.