1
general::
Phrase(s): if push comes to shove
Go to when push comes to shove.
McGrawhill's American Idioms And Phrasal Verbs
2
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Also, when push comes to shove. When matters must be confronted, when a crucial point is reached, as in If push comes to shove, the Federal Reserve Board will lower the interest rate, or They supposedly support equality, but when push comes to shove they always seem to promote a man instead of a woman. This term comes from rugby, where, after an infraction of rules, forwards from each team face off and push against one another until one player can kick the ball to a teammate and resume the game. Its figurative use dates from the 1950s. Also see the synonym IF WORST COMES TO WORST.
American Heritage Idioms