It is about demographics.
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The "freedom caucus"/ "tea party" are astro-turf constructs of Big Oil.  They represent the idea of the GWB presidency - the most Oil-controlled gov't in US history - after GWB became politically toxic.
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The target is old white, red-necked males with money.  That is a core vote Big Oil wants.  So they nominate jocks who are in car sales or in the plastics business, preferably evangelicals.
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US Health care is about race.
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That is why America is the only major OECD nation without single payer public health care.
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Why do they have it in for the poor?
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Because in their view the poor are brown or black - i.e., not "real" Americans, and certainly not deserving.   Their thinking has this sophistication: Why should good, honest, hard-working, God-fearing, white people have to pay for health care for lazy black people and Mexican rapists?
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For them, Trump's campaign was cat-nip.
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When Trunp says: Make America Great Again
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They hear:  Make America White Again.