tap out of

[Ostap]

Republicans frequently cite urban gang violence, most often in Chicago, in attempts to tap out of the gun control debate. While their redirections are often as misleading as they are cliche, those officials aren’t always as forthright as Masters about the racial undertones.
Daily Beast

Hello, teachers. How do I understand "tap" (or is it the phrasal verb "tap out"?)?

 

[jutfrank]

The metaphor comes from wrestling. To 'tap out', you tap your hand on the mat and this signals that you wish to quit the fight.